On Rehearing.
Bruce, J.We are now satisfied that our original opinion must be modified and the judgment be reversed, and that the learned trial court erred in its rulings as to the cross-examination of Dr. Chagnon, and failed to distinguish between the use of medical books for the purpose of cross-examination merely, and to test the knowledge and reading and *555accuracy of the witness who is upon the stand, and the use of such books in the examination in chief or in rebuttal, or by reading them, directly or indirectly, to the jury upon cross-examination, and not for the purpose of testing the learning, reading, or accuracy of the witness, but in order to get their contents and the opinions of their authors before the jury.
Although there is some conflict in the authorities and much obscurity of thought therein to be found, the distinction seems to be very clear. It is' that, where the expert has testified from his own experience, and from his personal experience alone, and has not based his opinions upon any specific authorities or upon the authorities generally, the scientific treatise may not be read, either directly or indirectly, to the jury or to the witness in the presence of the jury, so that in any way their authority may be obtruded upon them. Hypothetical questions may, of course, in all instances, be framed from the books, but the books themselves should not be paraded before the jury. Brown v. Springfield Traction Co. 141 Mo. App. 382, 125 S. W. 236.
Where, however, the witness has not testified as to the results of his experience alone, but of his reading also, or where the subject under consideration is of such- a nature that his opinion must necessarily be based upon his readings and the data and conclusions of the scientific authorities, rather than upon his individual experience, the witness may be cross-examined as to the authorities generally, and may be asked if he agrees with extracts which are read to him therefrom. This method of examination is allowed in these cases, not for the purpose of rebuttal, but to test the learning of the witness and the reliability and the nature of his data, and is permissible, even though no specific book has been referred to by him. It is allowed under the liberal rule which governs cross-examination, and not for the purpose of refuting the testimony of the witness by reading such authors into the evidence, which can only be done where the witness admits either in his examination in chief or in cross-examination that he has based his opinion upon such specific authors. See MacDonald v. Metropolitan Street R. Co. 219 Mo. 468, 118 S. W. 18, 16 Ann. Cas. 811. Where this is done, however, the proper practice is for the court to caution the jury that it is the testimony of the witness, and not what is read from the book, that constitutes evidence in the case. Ibid.
*556A distinction must be made between the cross-examination of a witness for the purpose of showing his lack of reading and training, and an attempt to overcome his evidence by reading medical works to the jury. The distinction is pointed out in the case of State v. Moeller, 20 N. D. 114, 126 N. W. 568, in which we said: “The fifth and sixth assignments of error relate to the sustaining of the state’s objection to the following questions, asked one of the experts': ‘Q. Don’t you know that the text-books dealing with obstetrics and gynecology lay it down as a fact of not uncommon occurrence for a woman in a pregnant condition to inflict injuries upon the walls of the uterus, and cause similar conditions to those which were presented by the uterus described in this case?’ and ‘Q. Does not Hearst say in his text-book that injuries to the internal walls of the uterus resulting in septicaemia, may be inflicted, and in fact not uncommonly are inflicted, by the pregnant woman herself?’ These questions were propounded to Dr. Larson, who conducted the autopsy. Lie was a most intelligent witness, but his experience was limited, and his testimony was based very largely upon knowledge gained from reading rather than from experience. Had these questions been submitted for the purpose of eliciting information as to the contents of text-books primarily, the ruling* of the court might be, and doubtless would have been, correct; but it is now claimed that they were submitted solely for the purpose of testing the accuracy of the witness’s knowledge and the correctness of his conclusions as an expert, that necessarily his opinions were based upon reading medical works, and that their bearing was upon the weight which should be given his testimony. If this was the reason assigned in the trial court, the ruling was error.”
When we apply these principles to the case at bar we become satisfied that the learned trial court erred in regard to the examination of Dr. Chagnon. It is clear from the record that Dr. Chagnon based his opinion largely upon his reading and upon the authorities, although he referred to no specific book. Counsel for defendant, then, should have been allowed to read to him from and to question him upon the medical authorities. “We cannot conceive,” says the supreme court of Nebraska in the case of Hutchinson v. State, 19 Neb. 262, 27 N. W, 113, “that it would be possible, by any rule of evidence, to base the testimony in chief of the witness upon his experience in obstetrics. For *557instance, the normal period of gestation, the probability of conception in the first act of intercourse, the length of the period of gestation in ease of the first as compared with subsequent children, the number of days that ill health caused by uterine disorders would shorten the period of gestation, if at all, and many other prominent elements in the case presented by the defense, would naturally and inevitably require the witness to go outside of the domain of experience as an obstetrician, and it seems to us that he very properly and truthfully answered that his testimony was based upon medical authorities. For the purpose, therefore, of testing his recollection as well as his knowledge, it was proper to interrogate him as to the teachings of those authorities, and, in case his testimony was incorrect, to confront him with them in order that he might be corrected, and the jury thus be rendered able to judge of the weight to which his testimony was entitled. It is insisted that the testimony was inadmissible because ‘the testimony of the witness shows that his opinion on the point in question was opposed to these same medical authorities.’ As we have shown, the testimony entered the domain of science, and the ground upon which the objection is founded appeals most strongly to the mind of the writer as cogent reasons why the cross-examination was proper.” It is, indeed, upon this fact, or absence of fact, of the witness having based his opinion in chief upon what he had learned from the books, that the cases may be distinguished. In the case of State v. Blackburn the court said: “He (the witness) had not .alluded to any authorities on his direct examination, as the witness had in Cronk v. Wabash R. Co. 123 Iowa, 349, 98 N. W. 885; nor had he based his opinion on what he had learned from the boohs, as in State v. Donovan, 128 Iowa, 44, 102 N. W. 791, and for this reason asked, as in Hutchinson v. State, 19 Neb. 262, 27 N. W. 113, what the several authorities taught. . . . In Connecticut Mut. L. Ins. Co. v. Ellis, 89 Ill. 512, the expert had said that he had read text-books in order to be able to state why he had diagnosed the case as delirium tremens, and paragraphs were read to him, and inquiry was made as to whether he agreed with the authors. This was approved on the ground that he had assumed to be familiar with the authors, and in no better way could his hnowledge on the subject be tested. ... In the case at bar the physician had based his opinion solely on his own experience and observation, and therefore it *558was error to cross-examine him on the state of the medical authorities, in order thereby to get their supposed teachings before the jury. . . . Moreover, the inquiry was not one depending so much on skill in the profession as upon observation in its practice.”
In the case of State v. Winter, 72 Iowa, 627, 34 N. W. 475, the question was asked upon the examination in chief, and not upon cross-examination. “He, [the witness]” the court said, “was then asked the following question: 'Have you read the article by Hr. Casselman, in the American Journal of Insanity, in which the author says, Mania,— instantaneous, temporary, fleeting, — a disease which breaks out suddenly like the sudden loss of sense by some physical disease; the subject is urged in a moment to automatic action, which would not have been foreseen ?” If you say you have read the above quotation, state whether the same agrees and accords with your knowledge and experience on the subject.’ On the objection of the district attorney the court excluded the question. It is not claimed that the question was asked with the view of laying the foundation for the introduction in evidence of the article referred to, but the object was to elicit the opinion of the witness. It will be observed, however, that the answer of the witness (which we assume would have been in the affirmative) would have been but a reiteration, in another form, of the opinion he had already expressed. He had already testified to the existence of the very form of mania referred to in the article. The fact or theory sought to be established was material and important, but as the witness had already clearly expressed his opinion as to its truth, the court did not abuse its discretion in refusing to allow the question, which, as we have said, sought only to elicit a reiteration of that opinion. The same witness was asked the following question, which the district court ruled was incompetent: 'State whether delusion or transitory mania is a condition recognized by medical authorities.’ Il would be admissible, perhaps, on the cross-examination of d medical expert, to inquire of him as to the teachings of the authorities in his profession. The object of such examination, however, would be to test the accuracy of the expert’s knowledge. But the question in this case was asked not with this view, but for the purpose of proving that the theory in question is taught by the authorities. But the works themselves were admissible in evidence, and they are the only competent evidence of what they teach.”
*559In the case of Connecticut Mut. L. Ins. Co. v. Ellis, 89 Ill. 516, the court on page 519 said: “On the other point made, no medical books were read to the jury as evidence or for any other purpose, and it will not be necessary to discuss the admissibility of such evidence. But on cross-examination of the attending physician, who made a diagnosis of the disease of which the assured died, and pronounced it delirium tremens, paragraphs from standard authors that treat of that disease were read to the witness, and he was asked whether he agreed with the authors, and that is complained of as error hurtful to the cause of defendant. The testimony of this witness was of the utmost importance, and certainly plaintiff was entitled to reasonable latitude in the cross-examination. The witness had given the symptoms of the disease with which the assured was affected, and pronounced it delirium tremens, and as a matter of right, plaintiff might test the knowledge possessed by the witness, of that disease, by any fair means that promised to elicit the truth. It will be conceded, it might be done by asking proper and pertinent questions, and what possible difference could make whether the questions were read out of a medical book or framed by counsel for that purpose. Ordinarily, the limits of cross-examination of a witness are within the sound discretion of the court, and usually the greatest latitude is allowable that can be consistently given, for the discovery of the truth. The witness in this case stated that he had read text-books that he might be able to state why he ‘diagnosed the case as delirium tremens/ Assuming to be familiar with standard works that treat of delirium tremens, it was not unfair to the ivitness to call his attention to the definitions given in the books, of that particular disease, and asking him whether he concurred in the definitions. IIow could the knowledge of the witness, of such subjects, be more fully tested? That is, in no just sense, reading books to the jury as evidence, or for the purpose of contradicting the witness. The rule announced may be liable to abuse. Great care should always be taken by the court to confine such cross-examination within reasonable limits, and to see that the quotations read to the witness are so fairly selected as to present the author’s views on the subject of the examination. That the cross-examination was in the presence and hearing of the jury could not, of course, be avoided, as the witness was examined in *560•open court. No material error appearing in the record, the judgment must be affirmed.”
In the case of MacDonald v. Metropolitan Street R. Co. 219 Mo. 468, 118 S. W. 78, 16 Ann. Cas. 811, the court said: “In framing •questions on the cross-examination of experts, counsel held in hand medical books, and formulated questions from their language. The books were not read to the jury, but the jury could see that the examiner read from them. This method of cross-examination was objected to. The court, over objections, permitted plaintiffs counsel to adopt the scientific terminology of the author, and put the propositions to witnesses obviously asserted by him, but repeatedly cautioned the jury that what was read from the book was not evidence, and the jury should pay no attention to it; that the only thing they could consider was the evidence that fell from the lips of the witness along the line of verifying the propositions put by the examiner. Samples of these •cautionary instructions are as follows (The court): ‘The jury will not give any more weight to anything Mr. Karnes reads from the books than they would to any other questions Mr. Karnes asks, unless the witness answers questions in the affirmative, thereby making it evidence in the case. . . . It is the answers of this witness, gentlemen ■of the jury, that is evidence in this case, and not the questions.’ Error is assigned on this phase of the trial, but the point is without soundness. It has been said that it is within the discretion of the court to permit medical books to be read to the jury (State v. Soper, 148 Mo. 1, c. 235, 236, 49 S. W. 1007, but undoubtedly the better and generally accepted doctrine is that the contents of such books are not admissible as independent evidence. [17 Cyc. 421; Union P. R. Co. v. Yates, 40 L.R.A. 553, 25 C. C. A. 103, 49 U. S. App. 241, 79 Fed. 1. e. 587 •et seq.] Judge Thayer in the last case puts the grounds of exclusion on, first, such evidence is not delivered under oath; second, there is no chance of cross-examining the author; third, medicine is not an exact science, doctors disagree, medical theories are subject to frequent modification and change. But while not independent evidence, and the question is a vexed one, yet there is a legitimate use of such books, at least on cross-examination, where the testimony has taken wide range and where skilled witnesses testifying as experts base their testimony on their knowledge derived from books as well as experience, as in this *561case. Here, defendant’s counsel had notified some of his witnesses that he was appealing to, and asking his doctors to draw from, their medical knowledge running back, say, two thousand years, and which could only be preserved, if at all, in book form, from the days when Socrates ordered a cock sacrificed to Esculapius, the god of medicine, and Hippocrates and Galen practised physic in Greece and Italy. Under such circumstances, we see no reason why counsel could not frame a proposition in medical science in the exact language of the author, and ask the witness whether he agreed to it, so long as this was done under the due guard of the cautionary instructions given by the court. Such is the doctrine of a learned and exhaustive note on § 440, Greenleaf on Evidence, 15th ed. p. 579, where it is said':' 'Moreover, it is a proper method of cross-examination, in order to test the learning of a witness who testifies as an expert, to refer to books of approved authority upon the subjects under investigation, and question him in regard to them.’ Mr. Justice Scott, in Connecticut Mut. L. Ins. Co. v. Ellis, 89 Ill. 1 c. 519, gives that proposition the indorsement of his strong pen, though stating that the mile is liable to abuse, and great care should be taken to prevent such abuse. He there says: 'Assuming to be familiar with standard works that treat of delirium tremens, it was not unfair to the witness to call his attention to the definitions given in the books, of that particular disease, and asking him whether he concurred in the definitions. How could the knowledge of the witnesses of such subjects be more fully tested? That is, in no just sense, reading hooks to the jury as evidence, or for the purpose of contradicting the witness.’ To the same effect is Hess v. Lowrey, 122 Ind. 1. c. 233 et seq., 7 L.R.A. 92, 17 Am. St. Rep. 355, 23 N. E. 156. In State v. Wood, 53 N. H. 1. c. 494, 495, Sargent, Ch. J., speaking to the point, said: 'As to Dr. Eerguson’s cross-examination, we see no reason for any objection to it. He had stated, as well he might, on direct examination, his knowledge of a particular subject, not from any experience or actual observation, but from what he had derived merely from reading and studying medical authorities. Then he was cross-examined as to that general reading, not by putting in the books, but by inquiries whether, in his general reading, he had not found particular theories laid down conflicting with the theory he had advanced as the result of his reading.’ Collier v. Simpson, 5 Car. & P. 73, goes further than the present case. *562There Tinclal, Oh. J., in speaking of a medical expert, says: T think you may ask the witness whether in the course of his reading he has found this laid down.’ And that was upon direct examination. The Chief Justice further says, U do not think that the books themselves can be read, but I do not see any objection to your asking Sir Iienry Halford (the witness who was the president of the College of Physicians) his judgment and the grounds of it, which may be in some degree founded on books, as a part of his general knowledge.’ AVe rule the point against defendant.”
In the North Dakota case of Kersten v. Great Northern R. Co. ante, 8, 147 N. W. 787, and where an examination of the record discloses the fact that the doctor had expressly stated that he had based his opinion upon the medical writers, the court said: “The fourth complaint of appellant relates to the cross-examination of defendant’s witness, Dr. Sihler. The doctor had given his opinion as to the effect upon the brain of a blow delivered directly above the injury. Upon cross-examination he was asked whether or not certain medical textbooks and authorities sustained a doctrine contrary to that held by th$ witness. It appears that the text-book to which reference was made was offered to the witness, and that the author at that time was a teacher of surgery in Johns Hopkins University. Thus the cross-examination was evidently in good faith to test the accuracy of the conclusion given by the expert who was upon the stand. Great latitude should be allowed in the cross-examination of experts to test their credibility and knowledge. Dilleber v. Home L. Ins. Co. 87 N. Y. 79; McFadden v. Santa Ana, O. & T. Street R. Co. 87 Cal. 464, 11 L.R.A. 252, 25 Pac. 681; Jones, Ev. 2d ed. § 389; Davis v. State, 35 Ind. 496, 9 Am. Rep. 760. AVe think the cross-examination proper.” See also State v. Moeller, 20. N. D. 114, 126 N. W. 568; MacDonald v. Metropolitan Street R. Co. 219 Mo. 468, 118 S. W. 78, and note thereto in 16 Ann. Cas. 810, 818.
In the case of Hess v. Lowrey, 122 Ind. 225, 7 L.R.A. 90, 17 Am. St. Rep. 355, 23 N. E. 156, we find the following: “Complaint is also made that the court erred in admitting in evidence extracts from certain books or treatises on surgery. It does not appear that extracts from the books were read in evidence, or admitted in evidence as such. In the cross-examination of a medical expert, the witness was asked *563whether certain statements were not made by certain writers on. surgery, the statement referred to being read from a booh held by counsel, as part of the question. It is recognized as a proper method of cross-examination, in order to test the learning of a witness who testifies as an expert, to refer to books of approved authority upon the subjects under investigation. Ripon v. Bittel, 30 Wis. 614; Connecticut Mut. L. Ins. Co. v. Ellis, 89 Ill. 516; Pinney v. Cahill, 48 Mich. 584, 12 N. W. 862; State v. Wood, 53 N. H. 484; Rogers, Expert Testimony, §§ 181, 182. The opinion of a witness may be tested by a cross-examining counsel by reading from medical books. 2 Best, Ev. pp. 882 — 884. Medical books may be read to the jury, not for the purpose of proving the substantial facts therein stated, but to discredit the testimony of experts who refer to books as authority for or in support of their opinions. Pinney v. Cahill, 48 Mich. 584, 12 N. W. 862.”
In Fisher v. Southern P. R. Co. 89 Cal. 399, 26 Pac. 894, 9 Am. Neg. Gas. 104, we find the following: “On cross-examination of Woolsey, a witness called as an expert by defendant, plaintiff’s counsel was allowed, against the objection of defendant, to read statements from medical works, and to ask the witness if he agreed with the authors. This is assigned as error. Plaintiff’s counsel defends the ruling here, on two grounds: (1) That the witness, on his direct examination, testified" to certain medical opinions and supported his statements by the assertion that they conformed to the authority of medical works; and he claims that the rule is that if the witness, either in direct or cross examination, relies in any manner upon the authority of medical works, generally or specifically, it is proper cross-examination to confront him with the works upon which he relies, to show that his understanding of them is incorrect, or to contradict him; and (2) that it is proper cross-examination to test the competency of the witness as an expert, or the value of his opinions. A careful examination of the evidence has convinced me that the rulings complained of cannot be defended upon either of these grounds, though the legal proposition be admitted. As to the first, it is plain that some of the extracts read have no reference to any opinions of the witness which he sought to sustain by a reference to medical writers, either generally or specifically, except in response to a direct question by plaintiff referring to such writers. As to the second ground, it is not so plain. The value of an effective *564cross-examination as a means of showing the incompetency of a witness or his lack of integrity and the true value of his testimony can hardly be overrated; and this is true in a special sense as to expert testimony, where the party may choose from the body of a profession those whose opinions are most favorable. It is quite natural, and certainly common, for one called as an expert to enhance his authority by his power of self-assertion, and there is reason to fear that these opinions are not always as impartial and indifferent as a judicial utterance should be. While it is to be regretted if in the proper exercise of the right of cross-examination it shall appear that certain medical writers of repute differ from the witness, and so a party will get the benefit of unsworn testimony, still this evil, unavoidable in the nature of things, is, in my opinion, not at dll commensurate with that which would deprive a party in such a case of the best touchstone known to legal science, by which to estimate the value of testimony. And if, on general principles, such questions are legitimate on cross-examination, I do not see how a party can be deprived of his right because such evil consequences may follow. All the works on medical jurisprudence which I have examined seem to sustain this position, and some cases, although they are not uniform. Brodhead v. Wiltse, 35 Iowa, 429; Connecticut Mut. L. Ins. Co. v. Ellis, 89 Ill. 516; Ripon v. Bittel, 30 Wis. 614; Pinney v. Cahill, 48 Mich. 584, 12 N. W. 862; State v. Wood, 53 N. H. 484. But since consequences are likely to follow which admittedly should be avoided if possible, such examination should be strictly limited to this one purpose, for which only it can be permitted. I think no fair-minded person can closely study this record without being convinced that the evidence was not put in with any such purpose. No doubt counsel offered it under the impression that it was justified as inconsistent with opinions which the witness had claimed were sustained by medical authorities. I have shown that the claim cannot be sustained on that ground. In fact, although the witness took issue with some statements read, they cannot fairly be said to contradict his evidence in any respect. They were evidently intended as evidence for the plaintiff, to sustain his theory of the case, and not to affect the competency of the witness or the value of his testimony. As it seems to me a new trial must be granted for this error, it becomes unnecessary to review the other assignments.”
*565In Greenleaf on Evidence, 16th ed. vol. 1, p. 269, § 162K, we find the following: “It has been thought by some courts that an expert witness may be discredited by reading an opposite opinion from a professional treatise, or by being asked whether opposing views have not been laid down by writers, or whether he agrees with certain opposing opinions then read; . . . and it is generally held that it cannot be done, except that where a witness has referred to a treatise, or to writers generally, as agreeing with him, the treatise may be shown not to agree with him, just as any other assertion of a witness may be disproved.”
In the case of State v. Wood, 53 N. H. 484, the witness (Dr. Ferguson) had several books upon the table during his direct examination, and was apparently about to read from them when he was prevented by the objection of the state. “Upon cross-examination, counsel for the state proposed several questions similar in form to the following: Have you found, in the course of your reading or study, this sentiment in regard to oil of savin (then reading from a sheet of writing paper in his hand) : ‘Death in an hour after taking it ?’ Have you also found this: ‘A woman took one hundred drops of oil of savin every morning for twenty days and went full time ?’ or this: . . . ‘Almost fatal consequences in producing abortion ?’ or this: ‘Its properties to produce abortion have been denied by late authors, of weight and reputation?’ or this': ‘Has no action as an abortive except like other irritants?’ The respondent objected that, if he could not be permitted to put in the books themselves, such questions were inadmissible; but the state were allowed to put the questions, subject to exception, and the witness answered several of them in the affirmative. Subsequently, upon redirect examination, the respondent asked several questions similar in form to the above, as to the existence in the books of statements tending to confirm the testimony of the witness on his direct examination.”
The court on page 494 of its opinion said: “As to Dr. Ferguson’s cross-examination, we see no reason for any objection to it. He had stated, as well he might, on direct examination, his knowledge of a particular subject, not from any experience or actual observation, but from what he had derived merely from reading and studying medical authorities. Then he was cross-examined as to that general read*566ing, not by putting in tbe books, but by inquiries whether, in his general reading, he had not found particular theories laid down conflicting with the theory he had advanced as the result of his reading. Collier v. Simpson, 5 Car. & P. 73, goes further than the present case. There Tindal, Ch. J., in speaking of a medical expert, says: T think you may ask the witness whether in the course of his reading he has found this laid down.’ And that was upon direct examination. The chief justice further says: T do not think that the books themselves can be read, but I do not see any objection to your asking Sir Henry Halford [the witness who was the president of the College of Physicians] his judgment and the grounds of it, which may be in some degree founded on books, as a part of his general knowledge;’ and see 1 Wharton, Crim. Law, 6th ed. § 50. It is settled, in Taylor v. Grand Trunk R. Co. 48 N. H. 304, 2 Am. Rep. 229, that a physician may give his opinion as an expert upon a subject concerning which he has had no practical experience, and where his knowledge is derived from study alone. This case, we think, fully sanctions the direct examination of this witness upon a subject where his knowledge was derived from books alone; and the cross-examination was simply the testing of the correctness of his opinion by the same standard upon which the opinion was founded, — the (authority of the medical books which he had read. We think this ruling was right.”
In speaking of this opinion, and in a case in which the general rule was announced that “an expert medical witness cannot be discredited by reading an opposite opinion from a text-book in the presence of the jury, and asking him whether it is correct, where he has in no way referred to the book to sustain his opinion or otherwise relied on it,” the supreme court of North Carolina, in the case of Butler v. South Carolina & G. Extension R. Co. 130 N. C. 15, 40 S. E. 770, said: “The last one [the opinion in question] relates to a cross-examination upon matters which the witness testified he had learned from certain medical authorities, not from experience or actual observation. The books were put in evidence, — were excluded — and the court held that upon the cross-examination counsel could be allowed to ask if the witness had not found particular theories laid down conflicting with the theory he had advanced as the result of his reading.”
In the case of Pinney v. Cahill, 48 Mich. 584, 12 N. W. 862, the *567court said: “The rule is acknowledged in this state that medical books are not admissible as a substantive medium of proof of the facts they set forth. But the matter in question was not adduced with any such view. The witness assumed to be a person versed in veterinary science; to be familiar with the best books which treat of it, and among others the work of Dodd. He professed himself qualified to give an opinion to the jury from the witness stand on the ailment of the plaintiff’s horse and its cause, and the drift of his opinion was to connect the defendant with that ailment. He borrowed credit for the accuracy of his statement by referring his learning to the books before mentioned, and by implying that he echoed the standard authorities like Dodd. Under the circumstances it was not improper to resort to the book, not to prove the facts it contained, but to disprove the statement of the witness, and enable the jury to see that the book did not contain what he had ascribed to it. The final purpose was to disparage the opinion of the witness, and hinder the jury from being •imposed upon by a false light. The case is a clear exception to the rule which forbids the reading of books of inductive science as affirmative evidence of the facts treated of. Ripon v. Bittel, 30 Wis. 614; 2 Whart. Ev. § 666.”
In the case of Byers v. Nashville, C. & St. L. R. Co. 94 Tenn. 345, 29 S. W. 129, the court said: “But we are of opinion that the objections to the usé of the book as first made were not well taken. The admission of such evidence is a matter largely in the discretion of the court, as well as the mode of conducting the examination. The witness Eravel was testifying not only as to the facts connected with the running of his train when the killing occurred, but also as an expert engineer, acquainted Avith and competent to testify as to the running of trains generally. When a witness is testifying as an expert, it is competent to test his hnowledge and accuracy upon cross-examination by reading to him, or having him read, extracts from standard authorities upon the subject-matter involved, and then ashing him whether he agreed or disagreed with the authorities, and comparing his opinion with those of the writer. Hess v. Lowrey, 122 Ind. 568, 7 L.R.A. 90, 17 Am. St. Rep. 355, 23 N. E. 156; Fisher v. Southern P. R. Co. 89 Cal. 399, 26 Pac. 894, 9 Am. Neg. Cas. 104; Richmond & D. R. Co. v. Allison, 86 Ga. 145, 11 L.R.A. 43, 12 S. E. *568352; 1 Greenl. Ev. 15th ed. § 440, note. We think it therefore admissible for the attorney to use the book in shaping his questions, and it was not error for him to require the witness to examine and read portions' of the book with a view of testing his knowledge by proper questions ; and this, so far as the record shows, is all that was attempted to be done in the first examination when the objection was made. But reading the book to the jury as evidence of the facts therein stated, and as a general rebuttal of the testimony of the expert, stands on a different basis. It does not appear that this was done during the examination and cross-examination of the defendant’s witnesses, but after they were through. Then the book was introduced again by the plaintiffs’ counsel, and several pages read to the jury, and no objection was at this time made. In the absence of such objection made when the book was thus offered and read for this purpose and in this way, there is no reversible error. See 1 Greenl. Ev. 15th ed. § 440, note e, in which the following propositions are laid down, and cases cited in support':' The weight of current authority is decidedly against the admission of scientific books in evidence before a jury, and allowing such books to be read from to contradict an expert generally.. However, it is a proper method of cross-examination, in order to test the learning of a witness who testifies as an expert, to refer to books of approved authority■ upon the subject under investigation, and question him in regard thereto. Scientific books may be used by the attorney in framing his questions for the witness. lie may read the question from such a book to the witness, either on direct or cross examination. Thompkins v. West, 56 Conn. 485, 16 Atl. 237. And if an expert has quoted a book, it may be read to him to show that he has misquoted it. Underhill, Ev. § 189; Ripon v. Bittel, 30 Wis. 614.”
In the case of Clukey v. Seattle Electric Co. 27 Wash. 70, 67 Pac. 379, the court said: “The sixth assignment embraced an objection to the manner in which the attorney for respondent conducted the cross-examination of the medical experts appointed by the court. The counsel asked the expert if such authorities did not lay down certain rules, — reading the language of the rule from the author s work, — and it is contended that it is an infraction of the rule of evidence against the admission of medical authorities. But we do not think the rule of law was announced to meet the practice of the kind complained of. *569These questions were propounded upon cross-examination for the purpose of testing the knowledge of the expert. It would have been competent for the attorney to have stated supposititious cases to the experts. He could properly have stated the rule from memory, asking the expert if such an author did not lay down such a rule. It seems there could be no tenable objection to his reading the rule to the expert. In fact, it is a more exact method, and less liable to make a wrong impression on the mind of the juror, than to cross-examine from memory/3
In the case of Brown v. Springfield Traction Co. 141 Mo. App. 382, 125 S. W. 236, the court said: “From the MacDonald Case,, as well as from authorities of other states, we glean the correct rule’ to be that an attorney may use a medical book to aid him in framing; questions to be asked of a physician testifying as an expert, but it is-not permissible to read from such books to the jury, and the court did not err in refusing permission to defendant’s counsel to read from such books to the jury in this ease.”
Again in the case of Louisville, N. A. & C. R. Co. v. Howell, 147 Ind. 266, 45 N. E. 584, we find the following: “Some contentions-made by appellant seem to be based upon a misapprehension of the facts, disclosed in the record. Objection, for example, is made to the exclusion of certain evidence sought to be elicited from Dr. Murphy, one of appellant’s witnesses. In the course of his re-examination this witness was asked by appellant’s counsel what was said in a certain named medical authority as to the difference between necrosis and caries of the bone, with a view to determine which of these diseases was indicated by the discharges from appellee’s wound; and counsel cited authority to show that on cross-examination, such questions are proper. There-is no doubt that, in order to test an expert’s knowledge, it is proper, on cross-examination, to read statements from writers of repute, who have treated of the subject concerning which the expert has testified,, and ask him questions touching the views advanced by such text-writers. Hess v. Lowrey, 122 Ind. 225, 7 L.R.A. 92, 17 Am. St. Rep. 355, 23 N. E. 156. The trouble with appellant’s contention is that the question here asked was not on cross-examination, and the evidence thus sought was but of a self-serving character.”
Again, in the case of Sale v. Eichberg, 105 Tenn. 333, 52 L.R.A. *570894, 898, 59 S. W. 1020, we find: “The third assignment is that the court erred in excluding, on cross-examination of Dr. Raymond, one of plaintiff’s witnesses, the reading of extracts from the standard work of Dr. Hamilton as to diagnosis and treatment of fractures like that of Eichberg. . . . Counsel stated he did not propose to introduce the book itself as evidence, but simply wished to test the witness as an expert, and the accuracy of his opinion and statements. It was held by this court in Byers v. Nashville, C. & St. L. R. Co. 94 Tenn. 350, 29 S. W. 128, viz., ‘when a witness is testifying as an expert it is competent to test his knowledge and accuracy, on cross-examination, by reading to him or having him read extracts from standard authorities upon the subject-matter involved, and then ashing him whether he agrees or disagrees with the authorities, and then by comparing his opinion with those of the writer.’ See also, Stoudenmeier v. Williamson, 29 Ala. 558. It is true the witness, after having been examined at great length in chief, finally, on cross-examination, said he did not claim to be an expert. The witness was a practising physician, and had expressed his opinion quite freely in respect of good practice and proper treatment in such cases. The defendant was entitled, on cross-examination, to test the witness’s knowledge in the manner indicated, and ’the court was in error in excluding the question propounded.” There can, indeed, be no doubt that the modem tendency, and certainly the tendency of this court is towards the freedom of cross-examination and quite a wide latitude therein. See Kersten v. Great Northern R. Co. ante, 3, 147 N. W. 787; State v. Moeller, 20 N. D. 114, 126 N. W. 568; State v. Apley, 25 N. D. 298, 48 L.R.A. (N.S.) 269, 141 N. W. 740. A distinction, however, must be made between legitimate cross-examination and an underhanded attempt to read the authorities to the jury. We think there was no such underhanded attempt in the case at bar, and that, though in the colloquy which afterwards ensued between court and counsel, and in a portion of the subsequent offer, counsel intimated that such could be done, it is clear to us that the primary purpose of the reading in the first instance was cross-examination, and cross-examination alone. If this was the case, and the ruling which prevented the reading in the first instance was incorrect, the rights of the defendant should not be jeopardized merely because, in addition to the reason which was first ad*571vanced therefor, others were subsequently asserted which were unsound. There can, we may add, be no distinction made between asking a physician if an author does not make some particular statement, and then .asking the witness what he thinks of the statement, which we inferentially at least held could be done in the case of State v. Moeller, supra, and the reading of the statement to the witness directly from the book in the first instance, and asking his opinion thereon. Williams v. Nally, 20 Ky. L. Rep. 244, 45 S. W. 874; Connecticut Mut. L. Ins. Co. v. Ellis, 89 Ill. 516.
The case at bar, then, comes within the permission, and not within the condemnation, of the decision. It is true that in his subsequent ■offer counsel asserted the right to use the books as evidence in them.selves, but this was only in a part of his offer, and he closed by saying: ■“And I also in this connection maintain that I am entitled, under the rules of legitimate cross-examination, to examine this witness thoroughly on that subject in the line that I have suggested to the court.” It is to be remembered, indeed, that he was interrupted as he was reading a statement from the work after the preparatory question, “Let’s see if you will agree with what I am going to read to you,” and though he seems in no way to have unnecessarily paraded the book, the court in answer to the question, “Then I understand, your Honor, it isn’t permissible to examine an expert witness as to whether or not he agrees with certain language that is laid down in a treatise,” answered, “Ton •can ask that, but you can’t read from the book.” Counsel for defendant then said: “Counsel for defendant desires to have the record show that he has no intention of offering the book in evidence; that his intention is to read from other like authorities, standard works on this .subject, certain hypothetical questions to be put to this witness as applied to the ease at bar, for the purpose of showing the jury that the child that is in controversy here was a full-grown normal child, and that under all the sound rules must have been begotten at a period of not less than 265 days and not to exceed 285 days, and that from the appearance of the child the witness is unable to state whether it was a 280-day child or a 265-day child.”
The door, indeed, seems to have been opened wide for cross-examination when on the direct examination of plaintiff’s witness, Hr. Chagnon, the witness was allowed to testify that "the medical authorities *572and physicians laid down as a maximum and minimum 270, 260, and 265 days, or a few days over;” and still further when he was allowed to correct himself, and in answer to a leading question, and over the objection of defendant’s counsel, to state that “it was a fact that some of the physicians and text-books laid down in minimum as low as 249 •to 285 days.”
When we come to the testimony of Dr. Vidal, and for the reasons-heretofore mentioned, we think the learned trial court committed no error. There was really no material difference in the two cases. Dr. Vidal had, it is true, on direct examination, referred to no particular authority, nor did he even on cross-examination agree with the authority read. He had, however, as in the case of Dr. Chagnon, based his opinion on the authorities generally, and it was merely proposed to examine him in regard thereto, and to read to him from them for that purpose. We now approve of the examination, not for the reason given in our original opinion, and of which we now entertain some doubt, but because the doctor had expressly stated that his opinion was based upon his readings and upon the authorities, and it was therefore perfectly permissible to show upon cross-examination that his. memory of what those authorities held was inaccurate, and to generally test the accuracy and extent of his reading and research.
It is true, there are some authorities which hold to a contrary rule to that which we have herein expressed. They are, however, few in number. Among them is the case of Mitchell v. Leech, 69 S. C. 413, 66 L.R.A. 723, 104 Am. St. Rep. 811, 48 S. E. 290. In this ease the court said: “The eleventh exception will next be considered. The record shows that the question arose in the following manner: ‘Doctor, is Lydson a standard medical work on genitourinary and venereal and sexual diseases? (Mr. Hart: I object. Medical books are not evidence, except in cases of insanity. Medical books are not evidence in cases of this character.) Q. I will ask him if that is good authority? (Mr. Hart: I object to that. Mr. Brice: This is an expert witness, and the witness had stated that the authorities, medical authorities — that is what the witness means — state that a man can have an injury so slight as not to be noticed at the time, and yet serious results follow. I am not introducing the authority. I am simply asking him whether this is an authority. The Court: The object of the question is to *573introduce the book ? Mr. Brice: I am simply going to ask him if tbis is an authority, and read bim a piece, and ask bim if that is good •authority or not? Tbe Court: That introduces tbe book. You wish to contradict or qualify tbe opinion of tbe doctor on tbe stand. Otherwise it would be irrelevant. Testimony excluded. (Exception taken.)’ Tbe presiding judge simply ruled that you could not contradict or qualify tbe opinion of tbe doctor on tbe stand by showing what some .author bad said. In tbis there was no error.”
Tbe case of Butler v. South Carolina & G. Extension R. Co. 130 N. C. 15, 40 S. E. 770, seems also to more or less bear out tbe point ■contended by tbe plaintiff. In it, however, there is no proof that tbe doctor in bis direct examination based bis opinion upon the authorities generally. Tbe same is true of tbe case of City of Bloomington v. Shrock, 110 Ill. 219, 51 Am. Rep. 678.
In tbe case of Chicago City R. Co. v. Douglas, 104 Ill. App. 41, tbe books were sought to be read on the examination in chief> and tbe case therefore is not in point. In tbe case of Hall v. Murdock, 114 Mich. 233, 72 N. W. 150, tbe books were actually read to tbe jury.
We, too, are not unmindful of tbe § 579 (595) of Jones on Evidence, on which tbe trial court based bis conclusions, and which states that “it is generally conceded, however, that where experts are examined as to questions of science they may give their opinions and tbe ground and reason therefor, although they state that such opinions are in some degree founded upon treatises on tbe subject. But it has been held inadmissible for such a witness to read to tbe jury from books, although be concurs in tbe views expressed, or even to state tbe contents of such books, though be may refer to them to refresh bis memory. . . . And when an expert has given an opinion and ■cited a treatise as bis authority, tbe book cited may be offered in evidence by tbe adverse party as impeaching testimony. But unless tbe book is referred to on cross-examination, it cannot be used for tbis purpose. It would be a mere evasion of tbe general rule under discussion, if counsel were allowed on cross-examination to read to tbe witness portions of such works, and to ask if be concurred in or differed from tbe opinions there expressed; hence this is not allowed.”
This section, no doubt, states tbe correct rule in regard to tbe examination in chief and rebuttal, and in regard to tbe actual reading of *574books to tbe jury in all cases. It also states tbe correct rule in regard to cross-examination where the specific book has neither been referred to nor has the witness based his opinion upon the authorities generally, but, instead, upon his own personal experience, and where his knowledge of and understanding of the authorities, as well as the extent of his general reading, is not a fit subject of inquiry. It does not, however, express either the general or the correct rule in cases where these, latter facts exist. The statement is too general. Only four cases, indeed, are cited by Mr. Jones in support of the proposition as made, and none of them bear out the contention of counsel for respondent, nor are applicable to facts such as are to be found in the one at bar. The cases cited are: Marshall v. Brown, 50 Mich. 148, 15 N. W. 55; People v. Millard, 53 Mich. 63, 18 N. W. 562; Bloomington v. Shrock, 110 Ill. 219, 51 Am. Rep. 678; State v. Winter, 72 Iowa, 627, 34 N. W. 475.
The first case, namely, that of Marshall v. Brown, supra, is more or less in point, but a reading of it will, we believe, disclose a quite apparent desire to read the book to the jury, rather than to test the knowledge of the witness. In the case of People v. Millard, 53 Mich. 63, 18 N. W. 562, the point was not merely not a decisive one in the case, but the readings which were under discussion appear to have been had on the direct examination of the witness, and their purpose to have been to bolster up his testimony, rather than to test his learning. The language of the opinion is itself a strong argument for the liberal examination of experts and the testing of their knowledge and information. The court, indeed, expressly states that if the witness is not well read he is not entitled to any credence as m% expert, and yet the case is cited as authority for the proposition that the extent- and thoroughness of that reading may not be probed into. The court in its opinion, in fact, merely says: -‘Another source of error quite as mischievous, and which the court evidently desired to prevent, but did not always do so, was the introduction of what is no more than hearsay evidence, in the shape of references to writers and books in such a way as to invoke their authority. As we have had occasion on more than one record to explain heretofore, expert evidence is only admissible on the theory that the jury cannot be supposed to comprehend the significance of facts shown by other testimony which needs *575scientific or peculiar explanation by those who do comprehend it. But this does not permit hearsay testimony of the written or spoken opinions of other persons, whom the jury have no means of examining as to their learning, their honesty, or their sources of special knowledge. Every medical and scientific writer bases much of his conclusions upon what he believes to be true in the reported facts and opinions of other men of science. Those facts may be correctly stated, or they may be assumed on small or no foundation. Those opinions may be taken carelessly at second hand, or they may have been thoroughly weighed before adoption. No one can tell whether a medical book or opinion is reliable or not, until he has applied himself, with some fitting preparation, to its study and criticism. The book may be good in part and bad in part, and neither court nor jury can presumptively ascertain its quality. No one has any title to respect as an expert, or has any right to give an opinion .upon the stand,. unless as his own opinion; and if„he has not given the subject involved such careful and discriminating study as has resulted in the formation of a definite opinion, he has no business to give it. Such an opinion can only be safely formed or expressed by persons who have made the scientific question involved matters of definite and intelligent study, and who have by such application made up their own minds. In doing so, it is their business to resort to such aids of reading and study as they have reason to believe contain the information they need. This will naturally include the literature of the subject. But if they have only taken trouble enough to find, or suppose they find, that certain authors say certain things, without further satisfying themselves how reliable such statements are, their own opinions must be of very moderate value, and, whether correct or incorrect, cannot be fortified before a jury by statements of what those authors hold on the subject. The jury are only concerned to know what the witness thinks, and what capacity and judgment he shows to make his opinion worthy of respect. If the opinion of an author could be received at all, it should be from his own words,— not in single passages, but in combination; and this, as has been heretofore held, cannot be done. It is excluded chiefly as both unknown as to value and as hearsay, and an attempt to swear to his doctrine orally would be hearsay still further removed, besides involving the other difficulty of needing interpretation and responsibility. A large *576part of this scientific evidence consists of repeated references for support and confirmation to the statements of authors, and, as might be expected, the different witnesses have not always read through the same glasses. To settle their differences the only resort must have •been to the very books, which no one claims were admissible. These references were not merely made on cross-examination to test the knowledge and veracity of the witnesses, but came in as frequently on direct examination. In Pinney v. Cahill, 48 Mich. 584, 12 N. W. 862, a witness who had asserted that a certain book laid down a certain proposition was allowed to be contradicted by showing, it did not. But it is' questionable whether the original assertion was properly drawn •out, although when made it was proper to let it be contradicted. It was distinctly held’in Marshall v. Brown, 50 Mich. 148, 15 N. W. 55, that attempts to evade the excluding rule by examining or cross-examining in such a way as to get an opportunity to get books before the jury could not be permitted.”
In the case of Bloomington v. Shrock, the opinion expressly approves •of the case of Connecticut Mut. L. Ins. Co. v. Ellis, to which we have before referred, as an authority in support of the conclusions which we have herein arrived at, and differentiates the case under consideration by the Illinois case, from the case at bar, by the express statement that “in the present case, it has been seen, the course pursued was entirely different. The witness based no opinion which he gave, upon the authority of books, and they were only brought in to impair his evidence on cross-examination.” In the case of State v. Winter, 72 Iowa, 627, 34 N. W. 475, the question was asked and the book sought to be read on the direct examination of the witness, and the authority therefore is in no way applicable here, nor in any way supports the proposition contended for by Mr. Jones.
Indeed, while further treating on the subject of the cross-examination •of experts, Mr. Jones himself cites with approval the case of Hutchinson v. State, 19 Neb. 262, 27 N. W. 113, to which we have before referred, and announces a general rule which appears to be clearly in harmony with that opinion and with the present holding of this court. In § 389 (391) of his Commentaries on Evidence, he says: “Not the least important part of the cross-examination is that which sub*577jects the qualification on wbicb tbe expert has been permitted to testify to a searching inquiry. He bas placed himself in tbe position of one capable, by reason of bis superior or peculiar knowledge, of announcing conclusions, wbicb are of weight according to tbe thoroughness of tbe knowledge wbicb prompted and is behind them. Therefore it is that tbe jury is entitled to know more fully the nature of bis qualification, tbe sources of bis knowledge, from wbicb be assumes to speak with special authority, and tbe grounds and reasons upon wbicb bis conclusions and opinions are based. For example, a medical witness had stated that bis testimony was based upon medical authorities, and be was then asked to state what tbe medical authorities at tbe time of tbe trial held upon tbe subject. Tbe question was proper. Eeese, J., said: ‘If tbe witness bad been testifying from bis experience and observation from a long course of practice, it was yet proper, for tbe purpose of ascertaining bis means of knowledge by a reference to tbe teachings of text-books of bis profession, and tbe scientific works from wbicb be bad drawn tbe theories and principles to wbicb be bad testified. . . . For tbe purpose, therefore, of testifying as to bis recollection, as well as to bis knowledge, it was proper to interrogate him as to tbe teachings of those authorities; and, in case bis testimony was incorrect, to confront him with them, in order that be might be corrected, and tbe jury thus be rendered able to judge of tbe weight to wbicb bis testimony was entitled. It is insisted that tbe testimony was inadmissible because “tbe testimony of the witness shows that his opinion on tbe point in question was opposed to these same medical authorities.” As we have shown, tbe testimony entered tbe domain of science, and tbe grounds upon wbicb tbe objection is founded appeal most strongly to tbe mind of tbe writer as cogent reasons why tbe cross-examination was proper.’ ”
For tbe reasons herein stated, we are now of tbe opinion that tbe judgment of tbe District Court should be reversed, and that a new trial should be bad. It is so ordered.