delivered the opinion of the Court. The first objection taken to the plaintiff’s right to recover, is founded upon the amendments, made by the demandants 111 their writ and declaration, after the cause came into this Court.
In general, amendments allowed at Nisi Prius, are considered as allowed at the discretion of the judge ; but whenever such amendments are of a character to affect the right of the plaintiff to recover, the propriety of such amendments is a fit subject to be reserved by the judge for the consideration of the whole Court, and the decision of such questions by the whole Court tends generally to preserve a uniformity of practice, which it is of importance to maintain. In regard to the amendments, which were made in the present case, we are strongly inclined to the opinion, that allowing the person, who acts in behalf of the minor demandants, to style himself prochein ami instead of guardian, cannot be deemec *348the introduction of a new party. It has been held, that infants suing by prochein ami, are liable to a judgment for costs, thereby considering them as the legal party plaintiff to the suit, and the prochein ami as only an attorney of record. Smith v. Floyd, 1 Pick. 275. It has also been held, that on a plea of abatement to the disability of the person of the plaintiff as an infant, an amendment may be allowed, permitting the introduction of*a prochein ami by whom the infant plaintiff sues. Blood v. Harrington, 8 Pick. 552.
Nor do we think that the change in the count, alleging their own seisin, was beyond the scope of those cases in which amendments are allowable. It is the same cause of action. It is the same title, defectively set out. The original count was manifestly defective, and inconsistent with itself, in setting out the seisin of the father and averring the disseisin of themselves. The original count however did allege tne disseisin of the plaintiff by the defendant, and the amendment, in this respect, merely permits the demandants to aver their own seisin, in terms, which might be implied by the averment, as it stood in the original count, that the defendant had disseised them.
But we think another objection quite fatal.
In comparing the two counts, the premises described are precisely the same. In the original count the demandants claim two -undivided sixth parts of the described premises, and in the amendment they demand the whole of the same premises. We are all of opinion, that this introduces a new substantive cause of action, and so is repugnant to the established rule, that new causes of action cannot be introduced by way of amendment. Under the original count, the plaintiffs could in no event recover more than one undivided third part of any portion of the described premises ; whereas, in fact, under the new count, by the verdict of the jury, they have recovered two undivided third parts of a distinct portion of the described premises, as distinguished and held by metes and bounds. Perhaps it is a conclusive objection against the amendment, that it did enlarge the subject matter of the suit and allow the demandants a chance to recover a larger share of the property than was originally claimed ; but the fact, that a larger share *349has been recovered, than could have been recovered under the original count, is a good practical illustration of the operation of this rule.
Without considering the points in order, we think there is one other exception which goes to the whole merits of the demandants’ title, and, in whatever form it may be presented, is decisive against it.
They claim title by descent from their grandfather, on the ground, that he died seised of the estate, and intestate ; and it is admitted that he was an alien.
We take the rule of law to be well settled, that where an alien, who may have taken an estate .by purchase, and who may thereby be seised de facto and hold until the commonwealth take measures to enforce the escheat, dies leaving children, who, if he were a citizen, would be capable of taking, still the estate vests presently in the commonwealth.
An alien takes to the use of the commonwealth. He must be held to take a freehold by purchase ; otherwise the title of the grantor would not be devested ; but he cannot hold. And though he may convey by grant, yet he can convey no greater estate than he has. His grant therefore could only convey an estate, defeasible at the suit of the commonwealth.
But it is held that the law does nothing in vain. It will not therefore cast upon any one a freehold, which he cannot hold. And inasmuch as the law will not allow the fee to be in abeyance, and as no one can take by the act of law, as descent is, for the reason already given, the law holds as a necessary consequence, that on the death of the alien, the freehold vests in the commonwealth immediately, without office found. Fox v. Southack, 12 Mass. R. 143 ; Fairfax v. Hunter, 7 Cranch, 603 ; Jackson v. Adams, 7 Wendell, 367.
But another reason equally strong, and of similar character, is, that an alien is deemed in law, to have no inheritable blood, and no one therefore can derive title through him or from him.
Ir the great case of Collingwood v. Pace, 1 Lev. 59, and 1 Ventr. 413, where there were two sons born in England ot an alien father, it was doubted and much discussed, whether *350the one could be heir to the other, because he must deduce his title by descent through his father, who had no inheritable blood ; but it was ultimately decided by a majority of the court, after an elaborate argument, that one should inherit to the other, though neither of them could inherit to the father, for the descent between them was immediate and the one should make his title in a mort d'ancestor, and as heir to the brother, without mentioning the father. This, as a general rule, is laid down as among the first principles of the law of real property. It is thus expressed by Lord Coke; “ And so it is, if an alien doth purchase land and die, the law doth cast the freehold and inheritance upon the king.” Co. Litt. 2 b. We therefore consider this defect of title decisive.
We have not supposed it necessary to consider, if Benjamin Slater, the elder, had been a British subject, what would have been the effect of that fact and the operation of the treaty of peace of 1783, and the treaty of 1794, upon the question we have been discussing, because there is nothing in the report to show whether he was, or was not, a British subject. If he was, those treaties may have an important bearing upon the subject.
New trial granted