¶1delivered the opinion of the court.
¶2This action was commenced by a subcontractor to recover a judgment against a principal contractor for furnishing certain stones for the erection of a railway bridge, and to enforce a mechanic’s lien therefor. The railway company paid into court more than enough money to cover the plaintiffs’ demand, and the plaintiffs had a verdict and judgment therefor, from which the defendant Crutsinger, the principal contractor, pros-ecutes this appeal.
¶3The errors assigned are: (1) That the court, after answer filed, improperly allowed William A. Long to be added as a co-plaintiff. It appears that this was done ■on the application of Long, and a suggestion that the cause of action had been transferred to him, and that the suit was being prosecuted in the name of Todd, the party in interest, for his benefit. Nothing appears in the record which puts the court in error in adding this party. The plaintiffs offered evidence tending to prove the assignment, after the commencement of the action, ■of the cause of action by Todd to Long for value ; and the jury, in answer to a special interrogatory, found that the assignment was an absolute assignment. Long was, therefore, a proper party plaintiff, and no error *147was committed in allowing him to be joined as such. Long should have been substituted as plaintiff in the place of Todd, instead of being joined with Todd as his co-plaintiff, as the evidence tended to show, and the jury found, that the entire cause of action had been assigned by Todd to Long. Michael v. Insurance Co., 17 Mo. App. 28. But it does not appear that the defendant suffered any prejudice from the fact that there was not a complete -substitution, or that his objection was urged on that ground.
¶4II. The other substantial assignment of error relates to the rulings of the court touching a paragraph of the answer of Crutsinger, which pleaded as a .setoff a promissory note of the original plaintiff, Todd, which Crutsinger had purchased of a third party, after the filing of the petition, but previously to the service •of summons upon him, Crutsinger. At the trial Crutsinger admitted that he purchased the note for the purpose of using it asan offset in this action. When he made this admission he stated himself out of court in respect of this offset. The rights of the parties to a civil ■action are ordinarily determined by the state of things which existed at and prior to the commencement of the action ; and in this state the filing of the petition is the ■commencement of the action, as it is all that the plaintiff can do to put in motion the machinery of the law. Gosline v. Thompson, 61 Mo. 471. That a demand cannot be set off, either in law or in equity, against the plaintiff’s demand, unless it existed as a demand against him in favor of the defendant at the time of the •commencement of the suit and had then become due, was decided in Reppy v. Reppy, 46 Mo. 571.
¶5III. The last assignment of error is, that the jury were biased, partial, and prejudiced; that their finding was contrary to the -evidence and the admissions of counsel, and that their general verdict was inconsistent with their special findings. As this assignment relates entirely to the manner in which the jury dealt with this matter of setoff, which, as we have seen, upon the *148established and admitted facts bad no standing in courts we need not consider it further than to say that it is not borne out in any degree by anything which appears-in the record. • :
¶6Judge Rombauer concurring, the . judgment is-affirmed. -