PELL, Circuit Judge.
Mayer Paving and Asphalt Company and Lee O. Mayer appealed from a judgment in favor of Material Service Corporation, a subsidiary of General Dynamics Corporation, on its counterclaim and from a judgment n. o. v. in favor of defendants on plaintiffs’ complaint.
Lee O. Mayer and her husband, Sidney R. Mayer, Sr., operated Mayer Paving Company as a partnership until the latter’s death in October 1964. Thereafter, the business was incorporated as [766]*766Mayer Paving and Asphalt Company. The plaintiffs will hereinafter be referred to collectively as Mayer Paving. Mayer Paving engaged in the asphalt paving business at all material times and had its principal place of business in Skokie, Illinois. Material Service Corporation was originally organized to produce and distribute crushed limestone, sand, and other aggregates in the paving and construction business. On December 31, 1959, General Dynamics Corporation acquired the assets of Material Service Corporation through a statutory merger. Thereafter Material Service was operated as a division, Material Service Division, until it was reincorporated as a wholly-owned subsidiary in March 1969.
Material Service operates five quarries in the Chicago area and sells to paving and construction contractors in Indiana and Illinois. Mayor Paving alleged and the jury from its verdict apparently concluded that during all relevant times2 Material Service was guilty of charging Mayer Paving higher prices for stone than it charged Mayer Paving’s competitors. The jury was unpersuaded by Material Service’s evidence concerning the cost and other claimed justifications of the various price differences.
Following the entry of judgment on the jury’s verdict, General Dynamics and Material Service moved for judgment n. o. v. on the ground that Mayer Paving had not established the jurisdictional prerequisite for a Robinson-Pat-man Act suit. The district court granted the motion in a memorandum opinion dated June 9, 1972. The court based its decision on its opinion that the factual situation here involved fell within the ambit of Borden Company v. Federal Trade Commission, 339 F.2d 953 (7th Cir. 1964), rather than Moore v. Mead’s Fine Bread Co., 348 U.S. 115, 75 S.Ct. 148, 99 L.Ed. 145 (1954). The district court concluded that Borden held that the Robinson-Patman Act did not cover a customer’s action for price discrimina-tions when all of the properly challenge-able sales were intrastate.
Section 2(a) of the Clayton Act, as amended, requires three different types of “in commerce” (i.e., interstate commerce) tests to be satisfied before jurisdiction can be established: first, the discriminator must be “in commerce” ; second, the challenged discrimination must occur “in the course of such commerce”; and third, “either or any of the purchases involved in such discrimination are in commerce. . . .” “The first two elements of the statutory ‘commerce’ provision are of lesser import .... Of prime decisional significance ... is the test that the challenged discriminatory transaction must itself occur ‘in’ commerce. Under that test, the applicability of Robinson-Patman is determined by this rule of thumb: at least one of the two transactions which, when compared, generate a discrimination must cross a state line.” Rowe, Price Discrimination Under the Robinson-Patman Act (1962), § 4.9, at 78-79. Such is the case in the present controversy as defendant does not challenge that it is itself “in commerce” and that the discrimination may have occurred in the course of commerce. The parties are deadlocked on whether or not the third “commerce” requirement has been met. Mayer Paving may not avail itself of the seemingly applicable language of § 3 of the Robinson-Patman Act, 15 U.S.C. § 13a, since that section provides no private right of action. Nashville Milk Co. v. Carnation Co., 355 U.S. 373, 78 S.Ct. 352, 2 L.Ed.2d 967 (1958).
Mayer Paving contends in reliance upon Moore that, since Material Service sold to a number of firms in Indiana at prices lower than those given Mayer Paving, the third commerce requirement [767]*767has been satisfied: “. . . once having established discrimination in commerce within the meaning of § 2(a), proof of competitive injury is sufficiently demonstrated when it is shown that Mayer Paving and other Illinois contractors are consistently charged substantially higher stone prices than their local competitors as well as Indiana contractors.”
General Dynamics, on the other hand, contends that in a case of second-line discrimination, that is, one in which the customers of the discriminator sue for damages to competitive position, such as is alleged by Mayer Paving, one of the discriminatory sales which is “in commerce” must be either to the plaintiff or to a competitor of the plaintiff. “That MS [Material Service] may have made interstate sales to Indiana contractors is irrelevant.2a Those Indiana contractors did not compete with Mayer, nor did the southern Cook County contractors who did small amounts of business in Indiana. . . . Therefore, this case only involves sales by MS of crushed limestone produced in Illinois to Mayer and its competitors for use in Illinois.” We are thus presented with a pure question of statutory interpretation.3
Initially, we should note that the scope of the Robinson-Patman Act amendments to the Clayton Act is significantly different from the Sherman Act’s in this very requirement that one sale be “in commerce.” Lehrman v. Gulf Oil Corp., 464 F.2d 26, 36 (5th Cir. 1972), cert, denied, 409 U.S. 1077, 93 S.Ct. 687, 34 L.Ed.2d 665; A. Cherney Disposal Co. v. Chicago & Suburban Refuse Disposal Association, 484 F.2d 751 (7th Cir., filed June 28, 1973) (p. 755). In contrast to the specific requirements of the Robinson-Patman Act, “it appears settled that only those activities are beyond the reach of the Sherman Act which are ‘purely local’ in the double sense that they (1) are not within the flow of interstate commerce and (2) have no significant effect on that flow.” ABA, Antitrust Developments 1955-1968, 39 (1968). Thus, we do not presently need to consider whether Congress has the power to reach such dis-criminations as are alleged by Mayer Paving. What we must determine is whether Congress intended to reach such discriminations.
“The Robinson-Patman Act as a whole was the product of such a complex series of interrelated legislative proposals that congressional intent is unusually difficult to decipher.” Recent Cases, 86 Harv.L.Rev. 765, 769 (1973). This is particularly true of the phrase requiring one of the sales to be “in commerce.” Compare Rowe, Discriminatory Sales of Commodities in Commerce: Jurisdictional Criteria Under the Robinson-Patman Act, 67 Yale L.J. 1155, 1166 n. 46 (1958), with Recent Cases, supra, 86 Harv.L.Rev. at 769-771.
We agree with the district court’s appraisal that the decision of this appeal is [768]*768dependent upon whether the situation involved activates the guidelines of Moore or of Borden. Unfortunately, neither is factually squarely in point and ultimately we must determine what the congressional.intent was with regard to the precise factual situation before us, in what we regard as a case of first impression. Nevertheless, because of their general pronouncements on the subject, we first turn to a consideration of Moore and Borden.
Certainly, the touchstone for analysis in the present area is Justice Douglas’s opinion for a unanimous Supreme Court in Moore. In that case, Moore was engaged in the bakery business in Santa Rosa, New Mexico, with none of its activities being in interstate commerce. The defendant was a corporation in competition with Moore for the local business in New Mexico. In addition to its intrastate business, the defendant was engaged in interstate commerce in that it sold bread in Farwell, Texas, with a truck originating in New Mexico. The plaintiff and the defendant became engaged in a price war in Santa Rosa, New Mexico, during which the defendant cut its price in Santa Rosa while holding its prices up in all other areas in which it was doing business, including its interstate business in Farwell, Texas. The Court held that such activity contravened the Clayton Act, as amended, even though the direct injury was purely intrastate. Mayer Paving relies heavily on the observation in Moore relating to the use of a treasury drawn from interstate business to finance impermissible local competition, 348 U.S. at 119, 75 S.Ct. 148; compare Cliff Food Stores, Inc. v. Kroger, Inc., 417 F.2d 203, 209 (5th Cir. 1969), and Willard Dairy Corp. v. National Dairy Products Corp., 309 F.2d 943 (6th Cir. 1962), cert, denied, 373 U.S. 934, 83 S. Ct. 1554, 10 L.Ed.2d 691 (1963), with Littlejohn v. Shell Oil Co., 456 F.2d 225, 229 (5th Cir. 1972), petition for rehearing en banc granted, 470 F.2d 997 (5th Cir. 1973).3a But that issue is not really involved in the present case since Moore was a case of primary-line injury, injury to a competitor of the discriminator, and the present case involved secondary-line injury, injury to one of the customers of the discriminator. That distinction is well-established, Federal Trade Commission v. Anheuser-Busch, Inc., 363 U.S. 536, 542-544, 80 S.Ct. 1267, 4 L.Ed.2d 1385 (1960), and it has substantial impact on the disposition of the present case. See also Rowe, Price Discrimination, supra.
Borden Company v. Federal Trade Commission, supra, which the district court below found to be controlling in the present case, while factually distinguishable is analogous to the present case. In Borden, this court refused to enforce the Commission’s order because the alleged discriminatory sales from Borden’s Portsmouth plant were without interstate indicia. “It [was] undisputed that the sales of milk were negotiated in Ohio, the milk was produced, processed and delivered in Ohio for resale in Ohio.” 339 F.2d at 955. There is no suggestion that the Portsmouth plant sold any of its products in interstate commerce. It is that fact which, as Mayer Paving notes, distinguishes Borden from the present case. It scarcely needs stating that the Borden Company was extensively engaged in interstate commerce. That is also true, although to a lesser extent, of both General Dy[769]*769namics and Mead’s Fine Bread in the Moore case, the latter defendant being one of several corporations having interlocking ownership and management in the same family. The pattern for growth of monopoly found by the Court in the situation in Moore, a primary-line injury, does not exist in this secondary-line injury case. In the case of the secondary-line injury of the present type,4 we are persuaded that the interstate character of General Dynamics’ overall business is not a controlling factor any more than it was in Borden.
However, General Dynamics did sell interstate from its Illinois operations and, as noted, the factual situation differs in this respect from Borden. Similarly, other cases cited by defendant are distinguishable either as involving allegations of purely intrastate sales, e. g., Belliston v. Texaco, Inc., 455 F.2d 175 (10th Cir. 1972), cert, denied, 408 U.S. 928, 93 S.Ct. 306, 34 L.E.2d 264, and Food Basket, Inc. v. Albertson’s Inc., 383 F.2d 785 (10th Cir. 1967), or relying on the “flow of commerce” doctrine in which the court found that the goods had come to rest, e. g., Cliff Food Stores, Inc. v. Kroger, Inc., supra, and Walker Oil Co. v. Hudson Oil Co. of Missouri, 414 F.2d 588 (5th Cir. 1969), cert, denied, 396 U.S. 1042, 90 S.Ct. 684, 24 L.Ed.2d 686 (1970), a doctrine which was inferentially undercut in Mr. Justice Clark’s opinion for this court in Bargain Car Wash, Inc. v. Standard Oil Co. (Indiana), 466 F.2d 1163, 1166 (7th Cir. 1972).
In turning then for our decision to the wording of the statute we are reminded of Mr. Justice Frankfurter’s appraisal that “precision of expression is not an outstanding characteristic of the Robinson-Patman Act.” Automatic Canteen Company v. Federal Trade Commission, 346 U.S. 61, 65, 73 S.Ct. 1017, 1020, 97 L.Ed. 1454 (1953). We shall also attempt to follow his admonition in the same case “to confine ourselves as much as possible to what is in dispute here.” For our present purposes, that which is in dispute is whether there is a violation of the Act where all of the purchases in which price discrimination existed made by both Mayer Paving and its competitors were intrastate and therefore not “in commerce.”
For the resolution of the particular dispute we again examine the words of the statute: “where either or any of the purchases involved in such discrimination are in commerce .” It is our view that the word “involved” when read against the underlying purpose of the anti-trust laws, to protect competition, requires that only the purchases by Mayer Paving competitors and by Mayer Paving itself be considered in determining whether “either or any” discriminatory sale is “in commerce.” We are fortified in this conclusion by the fact that § 2(a) specifies that a price discrimination is actionable only “where the effect of such discrimination may be substantially to lessen competition or tend to create a monopoly in any line of commerce, or to injure, destroy, or prevent competition with any person who either grants or knowingly receives the benefit of such discrimination, or with customers of either of them . . . .” Only those purchases which might injure competition are “involved” under the Robinson-Patman Act.
Mayer Paving attempts to argue applicability of Moore by variations of the factual situation here involved. We [770]*770are not concerned with other factual situations but only the one here involved and whether it calls into play the sanctions of the Robinson-Patman Act. Essentially, we have in the particular situation an analogue to standing. The customer has standing only to raise and compare those sales which are injurious to his competition. Cf. Federal Trade Commission v. Anheuser-Busch, Inc., supra, 363 U.S. at 342-343, 80 S.Ct. 1267. The competitor of the seller, on the other hand, has more freedom under Moore since the Court has declared that the competitor of the seller is involved in any sale which may be used to finance an intrastate price war in violation of the provisions of the Robinson-Patman Act. The analytical distinction involving the “competing customer” is discussed in Rowe, Price Discrimination, supra at 80. Similarly, the requirement that some evidence of competition exist to justify the invocation of this section of the Act is also found in National Lead Co. v. Federal Trade Commission, 227 F.2d 825, 836 (7th Cir. 1955), rev’d on other grounds, 352 U.S. 419, 77 S.Ct. 502, 1 L.Ed.2d 438 (1957). “For to the extent customers on different sides of a boundary line do not compete with each other, no adverse competitive effects on the customer level can ensue from the supplier’s price variations.” Rowe, Price Discrimination, supra at 179.
We do not find plaintiffs’ reliance on Littlejohn v. Shell Oil Co., supra, persuasive. That case involved what one commentator has called “indirect primary-line competition,” Case Comment, 57 Minn.L.Rev. 1035, 1040 n. 26 (1973). The court was concerned with the “underwriting” theory found in the general language in Moore, discussed above. Here, there is no allegation that the buyers who allegedly received lower, non-justified prices were related to General Dynamics in any way similar to the manner in which the gasoline stations were related to Shell Oil and American Oil in the Littlejohn case.
Once we so limit the referent of “purchases involved," the clear language of the statute requires us to affirm the judgment n. o. v. for defendant since on this appeal Mayer Paving has not contended that any of the sales to its competitors or itself were “in commerce.” 5
Mayer Paving also challenges the jurisdiction of the district court to enter judgment on the counterclaim. Mayer Paving in its original complaint named only General Dynamics Corporation as a defendant. In its answer, General Dynamics included a counterclaim on behalf of Material Service Corporation. After it filed a reply to the counterclaim, Mayer Paving moved for summary judgment or dismissal of the counterclaim on the ground that Material Service Corporation was not a party to the action. Following some procedural haggling, the district court6 in a memorandum opinion dated May 7, 1971, ordered Material Service Corporation joined as a party pursuant to Rule 19(a) (2)(i), Fed.R.Civ.P., and denied Mayer Paving’s motion for summary judgment on the basis that the counterclaim arose out of the transaction or occurrence that was the subject matter of the complaint and was compulsory pursuant to Rule 13(a), Fed.R.Civ.P., thus relieving Material Service from the necessity of establishing independent jurisdictional grounds.
General Dynamics referred to this problem as “a quibble as to terminology — a misnomer — which the previous attorneys for the plaintiffs and the attorneys for the defendant had not deemed of sufficient importance to correct by amendment of the complaint to add Material Service Corporation as a [771]*771formal defendant.” We do not view it as such, although some of the alleged discrimination went back to a time when Material Service, as a separate corporation, was the sole seller to Mayer Paving. Without any assertion of its relation to the complaint save for a vague reference as “Material Service Division of -General Dynamics, now Material Service Corporation,” various counterclaims were asserted by an entity never named in the complaint and never otherwise made a party to the cause. Defendant in its brief argues that any defect was waived by plaintiffs’ failure to object or otherwise raise the issue in its reply to the counterclaim, analogizing it to the waiver of the defense of lack of jurisdiction over the person found in Rule 12(h)(1), Fed.R.Civ.P. But that analogy is inapposite. Lack of subject matter jurisdiction is not waivable and must be raised by the court on its own motion, Rule 12(h)(3), Fed.R.Civ.P.
We turn then to the ground upon which the district court relied, that Material Service Corporation should be joined as a party under Rule 19(a) (2) (i) since the disposition of the action “in its absence may as a practical matter impair its ability to protect [its] interest.” The general policy of Rule 19, as with the Federal Rules of Civil Procedure in general, is “the impulse . toward entertaining the broadest possible scope of action consistent with fairness to the parties; joinder of claims, parties and remedies is strongly encouraged.” United Mine Workers of America v. Gibbs, 383 U.S. 715, 724, 86 S.Ct. 1130, 1138, 16 L.Ed.2d 218 (1966) (footnote omitted).
Under the Rule, Material Service Corporation would seem to be an interested party. The disposition of the action may collaterally affect its rights since it is the successor to the alleged principal violator of the law, Material Service Division. Thus, Material Service Corporation is arguably suitable for joinder under Rule 19(a) (2) (i). The only question is does it meet the general requirement of Rule 19(a) that “joinder will not deprive the court of jurisdiction over the subject matter of the action.” Thus, joinder may be inappropriate if it destroys diversity of citizenship. Jurisdiction in the present case is founded upon 28 U.S.C. § 1337, which gives the district courts original jurisdiction to hear cases arising under Acts of Congress “regulating commerce or protecting trade and commerce against restraints and monopolies.” Normally, this jurisdictional basis would be lacking since the present Material Service Corporation did not come into existence until after the date at which Mayer Paving stopped making the purchases alleged in the complaint. If we construe the assumption of the assets and liabilities 7 of the former Material Service Division of General Dynamics by Material Service Corporation as carrying over and giving Mayer Paving a right of action against the new corporation for the old division’s alleged violation of the antitrust laws, then we have a suitable jurisdictional basis for the joinder.
Once we can determine that Material Service Corporation was properly joined as a party defendant, it is clear that the counterclaim was properly within the jurisdiction of the district court. A compulsory counterclaim under Rule 13(a), Fed.R.Civ.P., “may be interposed without meeting jurisdictional requirements because it is auxiliary to the original action. . . . ” Chance v. Country Board of School Trustees of McHenry County, Ill., 332 F.2d 971, 973 (7th Cir. 1964). Since the counterclaim for the unpaid stone arises out of the transactions that are the subject matter of the complaint, the counterclaim is compulsory and there was no need for any independent jurisdictional basis. G & M Tire Co. v. Dunlop Tire & Rubber [772]*772Corp., 36 F.R.D. 440, 441 (N.D.Miss. 1964).
However, we need not rest our decision solely on the foregoing analysis supporting joinder of Material Service Corporation as a defendant. Disregarding form for substance, the court could have treated the motion as a motion under Rule 14(a), Fed.R.Civ.P., to implead Material Service Corporation as a third-party defendant. Had counsel for defendant in terms chosen this possibly preferable course the entire matter would have been considerably simplified. On the facts of this case, especially after our review of the pleadings and briefs, it would seem that the third-party complaint was what was really involved since General Dynamics was in effect saying that its new subsidiary, Material Service Corporation, had assumed all of the liabilities of the old Material Service Division and was, therefore, liable over to it for any violations of the Robinson-Patman Act committed by Material Service Division.
The sixth sentence of Rule 14(a) then provides the basis for Material Service Corporation’s claim against Mayer Paving: “The third-party defendant may also assert any claim against the plaintiff arising out of the transaction or occurrence that is the subject matter of the plaintiff’s claim against the third-party plaintiff.” The courts have split on the question of whether separate subject matter jurisdiction must be shown to sustain the third-party defendant’s claim against the plaintiff. See 6 Wright & Miller, Federal Practice and Procedure: Civil § 1458, at 311 n. 69 and § 1444, at 229-234, esp. nn. 90 & 91. Even the commentators are in disagreement. Wright and Miller favor ancillary jurisdiction in this type of claim, 6 Wright & Miller, supra, § 1444, at 234, and Moore indicates that it is inappropriate, 3 Moore, Federal Practice ¶ 14.27 [2] (2d ed.). We are persuaded that the better theory is to allow the claim to be brought under the ancillary jurisdiction power, especially since here the claim would have been a compulsory counterclaim subject to ancillary jurisdiction if the successor corporation had been originally named as a defendant. We agree with and adopt the reasoning of Circuit Judge Morgan in Revere Copper & Brass Inc. v. Aetna Casualty and Surety Co., 426 F.2d 709 (5th Cir. 1970), where this same question was analyzed and answered in favor of ancillary jurisdiction.
Thus, we affirm the district court’s jurisdiction of the counterclaim on the alternative grounds that Material Service Corporation was properly joined as a defendant or that it was properly made a third-party defendant.
For the reasons given hereinbefore, the judgment of the district court is affirmed.
Affirmed.
While this cause was on appeal, Lee O. Mayer died and Continental Illinois National Bank & Trust Company of Chicago, as administrator of the estate of Lee O. Mayer, deceased, was substituted in her place.