Prentice, C. J.

There are four reasons of appeal which in their substance resolve themselves into two: first, that there was error in submitting the case to the jury under the Federal statute; and second, that the instruction that the burden of proof, in the matter of assumption of risk, was upon the defendants, was erroneous.

The defendants’ contention in support of the first claim of error rests upon two fundamental propositions, to wit: (1) that the complaint clearly and unmistakably undertook to set out a cause of action at common law, and one cognizable by that law for the reason that the injuries complained of were received in intra-state commerce operations and employment; and (2) that any course of procedure, construction of pleading, or instruction, which would permit a recovery thereunder *638 by force of the Federal statute would be in effect to allow the introduction by the plaintiff of a new cause of action, and one against which the statutory limitation of time had run.

The complaint contains allegations which, if true, establish that the plaintiff’s primary right of personal security was invaded by the Central Vermont Railway Company’s wrong arising from its failure to perform toward him its-duty as his master, and that the plaintiff is entitled to a redress of the wrong so done him in damages recoverable in an action at law. The tort relied upon is fully set out. Whatsoever shortcomings there may be in the complaint, they do not concern the existence of a right of action. They concern the law invoked as furnishing the measure of damages recoverable. The situation is unusual in that we have two rules touching this subject prevailing and possessing equal authority in this jurisdiction, where the injury is received in railroad service. Our courts take judicial notice of both, and apply each as appropriate. If the employer is engaged in inter-state commerce, and the employee is so engaged when injured, there is one rule for the determination of the amount of recovery. If otherwise, there is a different rule.

The complaint contains no clear statement upon the pertinent matter of the employer’s character and the nature of the employee’s employment. It is not stated whether the operating corporation was engaged in inter-state or intra-state commerce. The only facts alleged from which an inference of any sort might be drawn is that its lessor, the New London Northern Railroad Company, owned a railroad in this State, and that the Central Vermont Railway Company was the lessee in operation of said railroad. It is not said that the railroad so owned and operated lay entirely within the State. That it did pot i» fact so lie the court, tak *639 ing judicial notice of the charter of the lessor, knew. 4 Private Laws, p. 996; 5 id. p. 261. But that matter aside, the allegation made is far from one that the Central Vermont Railway Company was an intra-state carrier. The situation in that regard is left unrevealed or uncertain.

Counsel for the defendants say that the manifest intention of the pleader was to give to the operating corporation an intra-state character, and for that reason to state an action cognizable at common law only. We fail to discover substantial ground for that conclusion. It is to be borne in mind that the complaint was drafted shortly after the handing down of the opinion of this court in Hoxie v. New York, N. H. & H. R. Co., 82 Conn. 352, 73 Atl. 754, in which we held the Federal statute unconstitutional, and as a consequence that there was but one measure of redress to be applied to situations like the present and that in Mondou v. New York, N. H. & H. R. Co., 82 Conn. 373, 73 Atl. 762, which may have led to the inference, although unjustifiable, that in any event a railroad employee entitled to maintain an action under the provisions of the Federal statute might, if he chose, waive that privilege, and sue the inter-state carrier at common law, and before the decision in the Second Employers Liability Cases, 223 U. S. 1, 32 Sup. Ct. Rep. 169, which held that the statute was constitutional, and the redress thereby provided exclusive in cases where it might be had. It well may be that the pleader was anticipating a common-law recovery; but that he intended to state a case without the purview of the Federal statute, and by that means bring it under the operation of the common law, is quite another proposition.

It is now clearly and unmistakably established that the Federal remedy exists as valid legislation, that it is exclusive where the conditions of the statute are met, *640 and that an opportunity to elect between the Federal and State remedies is never afforded. Second Employers Liability Cases, 223 U. S. 1, 55, 32 Sup. Ct. Rep. 169; St. Louis, S. F. & T. Ry. Co. v. Seale, 229 U. S. 156, 158, 33 Sup. Ct. Rep. 651; Chicago, I. & L. Ry. Co. v. Hackett, 228 U. S. 559, 567, 33 Sup. Ct. Rep. 581; De Atley v. Chesapeake & O. Ry. Co., 201 Fed. Rep. 591, 595. The complaint was not drawn in the light of these decisions and must not be judged in the light they have supplied. Judged in the light of the conditions existing when it was drafted, reasonable foundation for a conclusion that the pleader intended to state an intra-state commerce case, which could not be established, cannot be found in the allegations made. It is much more likely that he did not, contrary to the truth, so intend, but that his intention was to seek that to which he thought his client was entitled upon the facts as they were, which he had no purpose or intent to conceal or misstate, and which, in so far as he deemed them pertinent, he had undertaken to present to the consideration of the court.

The defendants’ first proposition not being well founded, we have no occasion to consider the soundness of the plaintiff’s counter-proposition, that even if such were the case, a change of allegation whose sole purpose was to indicate that the remedy to be applied was under the statute, and not as at common law, would not amount to a change of the cause of action.

The worst that can be said of the complaint from the defendants’ present standpoint is that it contains no allegations showing that it was brought under the Federal statute. Assuming, against the plaintiff’s contention, that such allegations form a part of the statement of a cause of action, the fault with the complaint is that it contains a defective statement of a good cause of action and not the-statement of a defective *641 cause of action. The distinction is important, and is attended with important consequences. Where a complaint contains a defective statement of a cause of action, that statement may be perfected later by amendment; but the statement of a defective cause of action is not the statement of any cause of action at all; and any process which will result in the statement of a good cause of action necessarily involves the introduction of a new cause of action. The perfection of a complaint of the former type, although defective in substance, by the process of amendment supplying material matter omitted from it, does not accomplish a change of the cause of action. “The rounding out of a complaint to cure a defective complaint, even in material matters, is not changing a cause of action nor adding a new cause, but merely making a good cause out of that which was a defective statement of a cause of action because of the omission of material allegations.” Lassiter v. Norfolk & C. R. Co., 136 N. Car. 89, 92, 48 S. E. 642.

The defendants place much reliance upon the opinion of the court in Union Pacific Ry. Co. v. Wyler, 158 U. S. 285, 15 Sup. Ct. Rep. 877, as supporting their position. The trial court, in withholding the desired leave to amend, also did. That case, brought in the State courts of Missouri, was one where the plaintiff had by clear and unmistakable allegations presented a case for the redress of personal injuries governed by the general law of master and servant. The amended complaint deserted this position and founded the right of action upon the provisions of a statute of Kansas, in which State the injuries were received, making an employer liable for the negligence of a fellow-servant of an injured employee. The tort originally complained of was the negligence of the master in the employment of an incompetent fellow-servant of the plaintiff. The amended complaint struck out this charge, and substituted as the *642 delict the negligence of a fellow-servant imputed to the master under the Kansas statute. There was thus a distinct change in the tort charged as the basis of liability. The present situation is a radically different one, and one to which the reasoning and conclusion in Missouri, K. & T. Ry. Co. v. Wulf, 226 U. S. 570, 33 Sup. Ct. Rep. 135, are more pertinent.

In Lassiter v. Norfolk & C. R. Co., 136 N. Car. 89, 48 S. E. 642, the administrator sued in North Carolina to recover for the wrongful death of a railroad employee. The complaint stated a good cause of action under the North Carolina law, had the death been caused in that State. As it appeared in the allegations that the death had been caused in Virginia, the plaintiff, after a demurrer, asked leave to amend his complaint by pleading a statute of Virginia which gave a right of action under the circumstances, thus basing his right of recovery upon that statute. It was held that this amendment, involving as it did an appeal to the Virginia statute, whereas the original complaint had been one, in form at least, under the North Carolina law, did not amount to a change of the cause of action. Other cases are referred to in the opinion in that case involving the. application of substantially the same principle.

The trial court erred in withholding from the plaintiff the desired leave to amend, for the reason assigned, but that error can be of no help to him here. The complaint remained unamended and barren of allegations showing the application of the Federal statute. The admitted allegations of the third defense, however, brought the pertinent facts upon the record, and supplied the absence of them in the complaint. Brooke v. Brooke, 1 Sid. 184; United States v. Morris, 23 U. S. (10 Wheat.) 246, 286; Slack v. Lyon, 26 Mass. (9 Pick.) 61, 65; Rubens v. Hill, 213 Ill. 523, 537, 72 N. E. 1127; Hedderly v. Downs, 31 Minn. 183, 186, 17 N. W. 274. This doc *643 trine of express aider is one which we have approved as resting upon principles of justice. Wall v. Toomey, 52 Conn. 35, 38. Under its application the complaint, defective though it was for lack of allegation of material facts, had its defects in that respect cured, and the missing allegations supplied by their subsequent averment by the defendants and admission by the plaintiff. A plaintiff may not, of course, avail himself of the allegations of an answer to introduce or prosecute a new cause of action against which a statutory limitation has run; but he may do so to help out a defective statement of his cause of action. That is the situation in this case. The defendants’ allegations accomplished the same curative result that was attempted to be accomplished by the proposed amendment. It matters not that these allegations came into the pleadings more than two years after the plaintiff’s injuries were sustained. The effect of them was not to give to the plaintiff a new cause of action, but to help out the original cause of action upon which suit had been brought within the statutory period.

The court correctly charged that the burden of proof in the matter of the assumption of risk was upon the defendants. Where the risk to which the servant is exposed is one that arises from the negligent conduct of the master in having imported into the situation a factor of peril not ordinarily incident to the business in which the servant is engaged, it is, in legal terminology, an extraordinary one. In such cases it is not incumbent upon the plaintiff to either allege or prove want of knowledge and nonassumption. The law upon this general subject is fully stated in Worden v. GoreMeenan Co., 83 Conn. 642, 645, 78 Atl. 422. See also Baer v. Baird Machine Co., 84 Conn. 269, 273, 79 Atl. 673.

The risk here complained of arose, as alleged, from *644 the negligent erection of a switch-stand in dangerous proximity to one of the tracks in the railroad yard, and the negligent failure to have a warning light upon it. This was not a risk ordinarily incident to the railroad service in which the plaintiff, as a brakeman, was employed, but one arising from the defendants’ negligence. The plaintiff may have known of it, and have voluntarily assumed it, but he did not do so by entering into his employment. If such was the fact, it was incumbent upon the defendants to plead and prove it. Their pleadings were framed upon that theory and correctly so.

There is no error.

In this opinion the other judges concurred.