after stating the case as above, delivered the opinion of the court.

Inasmuch as no issue of former adjudication was made, tried, and determined in favor of defendants in error, the questions that are duly presented by the present record remain at large.

i. Prior to the act of March 3, 1875 (18 Stat. 472), if the necessary diversity of citizenship was duly pleaded in the declaration or bill of complaint, evidence to the contrary was inadmissible, except under a plea in abatement in the nature of a plea to the jurisdiction, and a plea to the merits was a waiver of the plea in abatement. Farmington Village Corp. v. Pillsbury, 114 U. S. 138, 5 Sup. Ct. 807, 29 L. Ed. 114; Hartog v. Memory, 116 U. S. 588, 6 Sup. Ct. 521, 29 L. Ed. 725. By that act it was provided:

*804“That If, In any suit commenced in a circuit court or removed from a state court to a circuit court of the United States, it shall appear to the satisfaction of said circuit court, at any time after such suit has been brought or removed thereto, that such suit does not really and substantially Involve a dispute or a controversy properly within the jurisdiction of said circuit court, or that the parties to said suit have been improperly or collusively made or joined, either as plaintiffs or defendants, for the purpose of creating a ease cognizable or removable under this act, the said circuit court shall proceed no further therein, but shall dismiss the suit or remand it to the court from which it was removed, as justice may require.”

Of the effect of this act in modifying the former procedure, the supreme court, in Hartog v. Memory, supra, said:

“Neither party has the right, however, without pleading at the proper time and in the proper way, to introduce evidence, the only purpose of which is to make out a cause for dismissal. The parties cannot call on the court to go behind the averments of citizenship in the record, except by a plea to the jurisdiction, or some other appropriate form of proceeding. The cause is not to be tried by the parties as though there was a plea to the jurisdiction, when no such plea has been filed. The evidence must be directed to the issues, and it is only when facts material to the issues show there is not jurisdiction that the circuit court can dismiss the ease upon the motion of either party. If in the course of a trial it appears, by evidence which is admissible under the pleadings, and pertinent to the issues joined, that the suit does not really and substantially involve a dispute of which the court has cognizance, or that the parties have' been improperly or collusively made or joined for the purpose of creating a cognizable case, the court may stop all further proceedings and dismiss the suit.”

Defendants in error rely on this case to show that, since plaintiff in error filed his plea in abatement with his pleas to the merits, the evidence as to jurisdiction cannot be considered. But in Morris v. Gilmer, 129 U. S. 315, 326, 9 Sup. Ct. 289, 32 L. Ed. 690, the doctrine of Hartog v. Memory on this point was denied, and it was held that:

“The act of 1875 imposes on the circuit court the duty of dismissing a suit if it appears at any time after it is brought, and before it is finally disposed of, that it does not really and substantially involve a controversy of which it may properly take cognizance. And the statute does not prescribe any particular mode in which such fact may be brought to the attention of the court. It may be done by affidavits, or the depositions taken in the cause may be used for that purpose. However done, it should be upon due notice to the parties to- be affected by the dismissal.”

And in Anderson v. Watt, 138 U. S. 694, 701, 11 Sup. Ct. 449, 450, 32 L. Ed. 1078, the court said:

“Under the act of March 3, 1875, the objection to the jurisdiction upon a denial of the averment of citizenship is not confined to a plea in abatement or a demurrer, but may be taken in the answer, and the time at which it may be raised is not restricted. Although the averment as to citizenship may be sufficient, yet, if it appear that that averment is untrue, it is the duty of the circuit court to dismiss the suit; and this court, on appeal- or writ of error, must see to It that the jurisdiction of the circuit court has in no respect been imposed upon.”

It is manifest, therefore, that defendants in error are mistaken in claiming that the question of jurisdiction on the necessary diversity of citizenship is not before the court. But the question is not, as plaintiff in error contends, whether defendants in error have discharged the burden of proving that Elbert W. Shirk was a citizen of Indiana. *805The proper allegation of jurisdictional facts, prima facie, was true. Simply to deny that Elbert W. Shirk was a citizen of Indiana would not show a want of jurisdiction. He may have been a citizen of some other state than Illinois, whereof plaintiff in error was a citizen. That Elbert W. Shirk was a citizen of Illinois was a material and necessary allegation. It was an affirmative averment, the burden of proving which, even under a proper plea in abatement, would have fallen on plaintiff in error. Sheppard v. Graves, 14 How. 505, 512, 14 L. Ed. 518; De Sobry v. Nicholson, 3 Wall. 420, 18 L. Ed. 263. Under the plea in the present case, the office of which was no broader than a motion or a suggestion to the court to protect itself from imposition, the burden most assuredly was upon the moving party. Plaintiff in error introduced no evidence on the subject. The evidence of defendants in error does not establish that Elbert W. Shirk was a citizen of Illinois, and that the circuit court was imposed upon.

2. The legal title of the mortgagee is recognized only for the benefit of the holder of the mortgage debt. Against all other persons the mortgagor is the legal owner of the estate. Barrett v. Hinckley, 124 Ill. 32, 14 N. E. 863, 7 Am. St. Rep. 331; Seaman v. Bisbee, 163 Ill. 91, 45 N. E. 208. When the lease was made to Smith, Shirk therefore had perfect authority to reserve the covenant against assignment without written consent. Furthermore, neither Smith nor Adams will be heard to deny that his landlord had good title when the lease or when the assignment was made. Cox v. Cunningham, 77 Ill. 545; Hardin v. Forsythe, 99 Ill. 312; Sexton v. Carley, 147 Ill. 269, 35 N. E. 471.

3. The Illinois statute (chapter 80, § 14, Starr & C. Ann. St.) preserves to grantees of the reversion of demised lands the same remedies for the recovery of rent that the lessor had. It is conceivable that, if Elbert W. Shirk had conveyed in severalty to various grantees different parcels of the demised land, a grantee might not enter upon his portion for breach of a covenant made with the owner of the whole. But here all the owners in common of undivided interests are seeking to recover for delinquent rents. Their right to recover is clear, if Elbert W. Shirk could have recovered, had he remained the sole owner.

4. It is said that the written consent is inefficient, because defendants in error did not execute it as trustees, but only as individuals; that defendants in error, in both capacities, accepted rent, and thereby waived the requirement of written consent to assignments; and that, the restriction being gone, Adams’s assignment to Petterson was binding on defendants in error, and Adams was relieved from paying rent thereafter. The provision for written consent was for the benefit of the lessor. One can waive a safeguard for his own protection. He may thereby cut himself off from a particular defense or a particular remedy, but in other respects he creates no rights in his adversary. The claim of plaintiff in error that the acceptance of .rent from him was a binding recognition of the validity of Smith’s assignment to him, and of his right to assign without written consent, proves that consent by mouth or act is as effectual as consent in writing for the protection of the assignee. It is therefore immaterial whether consent, unquestionably given by act, was also duly expressed in writing. Im*806material^ top, in view of the answer to be given to the next contention of plaintiff in error, is the question whether the assignment to Petterson destroyed the privity of estate between the parties to this action. The ending of the privity of estate would not affect the privity of contract, if such a relation had been created and was existing between the parties.^ And this brings up the central point of the case.

5. Did Adams enter into a lawful contract with defendants in error, under which he became bound personally to pay rent, taxes, and special assessments until the end of the term? In the assignment of the lease he agreed that he “accepts and assumes all the terms, covenants, and agreements in said lease contained, and will personally comply with them and be bound by them, and will keep and perform all the covenants and agreements in said lease contained.” Among the covenants and agreements in the lease was one for the payment of rent, taxes, and special assessments. Smith had agreed in the lease not to assign to any one who would not assume and discharge all the obligations of the original lessee. If the assignment had not contained Adams’s assumption, or if defendants in error (or arbitrators provided for in the lease) had not found Adams to be responsible, defendants in error would not have needed to accept Adams as tenant. Their acceptance of him was a good consideration for his promise to them to keep and perform all the covenants and conditions in the lease. True, Adams’s promise was expressed in writing in the assignment. But it was necessary that the assignment should contain Adams’s assumption, and should be submitted to defendants in error for their approval and acceptance. Their acceptance brought them into direct contractual, relations with Adams. Webster v. Fleming, 178 Ill. 140, 52 N. E. 975; Springer v. De Wolf, 194 Ill. 218, 62 N. E. 542; Consumers’ Ice Co. v. Bixler, 84 Md. 437, 35 Atl. 1086; Lindsley v. Brewing Co., 59 Mo. App. 271.

6. For that Adams’s promise was made to defendants in error, Smith’s release of Adams was as ineffectual as any stranger’s.

7. The rate of interest in the lease was lawful when the lease was made. The subsequent change in the statute could not make the interest provisions usurious as between the original parties. After the change, Adams assumed and agreed to carry out Smith’s contract. In one’s mere assumption of another’s valid obligation, there can be no usury.

8. In Illinois the right of a creditor to maintain an action at law against one who has assumed the debt has been definitely decided. Dean v. Walker, 107 Ill. 540, 47 Am. Rep. 467; Webster v. Fleming, 178 Ill. 140, 52 N. E. 975. In Union Co. v. Hanford, 143 U. S. 187, 12 Sup. Ct. 437, 36 L. Ed. 118,—a suit begun in the circuit court for (the Northern district of Illinois,—the supreme court recognized that by the law of Illinois a mortgagee may sue at law a grantee, who, by rthe terms of an absolute conveyance from the mortgagor, assumes the ¡payment of the mortgage debt, and, respecting the right and the remedy in the national courts, held that:

"The question whether the remedy of the mortgagee against the grantee is at law and in his own right, or in equity and in the right of the mortgagor only, is to be determined 'by the law of the place where the suit is brought.”

*807In the same case, however, it was said:

“By the settled law of this court, the grantee is not directly liable to the mortgagee, at law or in equity; and the only remedy of the mortgagee against the grantee is by bill in equity in the right of the mortgagor and grantor, by virtue of the right in equity of a creditor to avail himself of any security which his debtor holds from a third person for the payment of the debt.”

Plaintiff in error insists that the part of the Hanford Case which rales that the creditor’s remedy will be administered according to the law of the place (the state) wherein the suit is brought in the national court has been discredited by later cases (Furnace Co. v. Witherow, 149 U. S. 574, 13 Sup. Ct. 936, 37 L. Ed. 853; Lindsay v. Bank, 156 U. S. 485, 15 Sup. Ct. 472, 32 L. Ed. 505), holding that a cause of action inherently equitable must be brought on the equity side of the national court, although the particular right could have been asserted in an action at law in the courts of the state in which the national court is sitting. To affirm the judgment in the present case it is unnecessary, in our opinion, to deny the validity of this contention, because, for reasons hereinbefore stated, Adams’s promise was made to defendants in error, who accepted and acted upon it, and because no relief was demanded or obtained that cannot be satisfied by an execution at law.

The judgment is affirmed.