Ok. Suppose you’re a Jew and the one next to you is goy. His donkey is carrying an as yet unborn offspring, and you buy it from him. Assuming that this will have been the first offspring that the donkey in question has produced, are you obligated to treat it as a peter chamor and redeem it? The Mishnah says no. Now suppose that you have one (you have a donkey that’s carrying an offspring) and you sell it to him (the as yet unborn offspring). The Mishnah says two things. First, you are not really allowed to sell it to him. And second, if you sold it to him anyway, you are not obliged to treat it as a peter chamor. What if you and the goy are partners in the ownership of a donkey or of its as yet unborn foal? There too, the foal is not treated as a peter chamor. What, now, if you have entered into an arrangement with him, whereby you get a share in the donkey’s offspring, receiving some of them? Here too, the firstborn offspring you receive is not subject to the requirements of peter chamor. What if, instead of an arrangement whereby you receive some of the produce of his donkey, you enter into one by which he receives some of the produce of your donkey? Are you required to treat the firstborn foal of this donkey of yours as being subject to the laws of peter chamor? No. In each case, the criterion of being that of a yisra-el has not been met.