The opinion of the court was delivered,

The railroad, property, estate and franchises of the Pittsburg and Steubenville Railroad Company, mortgaged to Thomas McElrath to secure the payment of $1,000,000 of bonds, were sold under a decree of this court for $1,960,000, and the distribution of this sum is the proceeding now before us. The inquiry of the master was limited solely to the distribution of the money among the parties entitled to receive it under the decree. He could not go behind the decree to inquire whether it was rightfully made or whether the parties before him were entitled to hold a position different from that which the decree assigns to them. If George M. Chapman, as a holder of bonds under the second mortgage of $500,000, was erroneously postponed in payment to the holders of the bonds under the first mortgage, it was his business to come before the court to review the decree against the second mortgage or obtain a rehearing. The bondholders in such a mortgage as this is are not the parties to it, though they have rights under and claim through it. The true party is the trustee to whom it is given as the security for all the bonds issued under it. It would be impossible, and if possible, excessively inconvenient, to make all parties holding the bonds, which are separate instruments, parties to the decree of foreclosure and sale under the mortgage. The bonds are payable to bearer and pass by delivery, and who the holders are after they pass into the current of business cannot he told. Hence, the trustee is the party to be summoned to defend the interest of those who claim *41under the mortgage. The bondholders are privies in interest, and may come in to defend pro interesse suo, but their rights are affected by the decree against their trustee. Chapman, therefore, as a holder of bonds under the second mortgage, is not a stranger claiming collaterally, but must come in under the mortgage. He does not stand in the attitude of another creditor claiming a right to attack the decree or judgment of an opposing creditor upon the ground of collusion or fraud between the plaintiff and defendant in the judgment, but he is affected by the decree itself against his own trustee. These principles will be found to be sustained by the following eases: Dougherty’s Estate, 9 W. & S. 189; Dickerson’s Appeal, 7 Barr 255; Thompson’s Appeal, 7 P. F. Smith 175; Clark v. Douglass, 12 Id. 408. The bill was filed against the trustees of the $500,000 mortgage and the decree made against them. If there were any collusion on the part of the trustee and the plaintiffs affecting the interest of the bondholders under the second mortgage, they had their remedy against the colluding trustee, or by application to this court in proper time and form to set aside the decree. The master was right, therefore, in refusing to hear all the offers of evidence made by the exceptant, except the 5th and 13th. Those two taken together presented a question in the distribution itself. In connection with so much of the 9th offer as alleges that the Pennsylvania Railroad Company is the real owner of the bonds presented by William T. Howard, Esq., for payment under the first mortgage, the 5th and 13th offers allege in substance that Greorge M. Chapman is the owner of $30,000 of the first-mortgage bonds now presented for payment by the Pennsylvania Railroad Company, and was fraudulently induced by that company to exchange them for $30,000 of the second-mortgage bonds. He claims, therefore, as the true owner of these $30,000 of first-mortgage bonds to receive the money to which they are entitled in the distribution. The question thus presented is simply one of ownership, and it was competent for the master to hear and determine it, as we held in Souder’s Appeal, 7 P. F. Smith 498. In other respects we perceive no error in the master’s report. We, therefore, sustain so much of the first exception of Gr. M. Chapman to the report as embraces the question of the ownership of the $30,000 of first-mortgage bonds above stated, and remand the report to the same master for a hearing and decision of this question.