Assuming that evidence upon the question whether anything was due from the defendant to the plaintiff would ordinarily be admissible in aggravation or mitigation of damages, we are of opinion that the defendant had waived and lost her right to go into this issue by her conduct at the trial. The plaintiff, in making out her case, offered evidence to show an indebtedness from the defendant to her, which was excluded upon the objection of the defendant. At a later stage of the case, the defendant offered evidence to show that nothing was due the plaintiff. To admit the evidence might be unfair and unjust to the plaintiff, who might not be prepared at that time to meet an issue which, on the defendant’s motion, had been excluded from the case. We think the defendant had waived and lost the right to insist upon introducing evidence upon this issue; and that its admission or rejection was within the discretion of the presiding justice, to the exercise of which no exception can be taken. Commonwealth v. Marks, 101 Mass. 31. Shaw v. Stone, 1 Cush. 228, 243. Exceptions overruled.