Question (R. Chanina to R. Acha): What's the meaning of the Mishnah's phrase (Zevachim 101(b)) 'it is treated as the produce of a gentile'? Does it literally mean as his produce? This will cause a problem, as he will use these fruits to tithe fruits elsewhere!

Answer (R. Acha): Did Chazal say that it is Tevel for everything? They said as a stringency that it's Terumos and Maaseros should be given, but not that he can use these fruits to tithe other fruits.

R. Chanina should not have come against R. Acha in this matter, as his answer is sound.

(R. Chiya bar Bun citing R. Yosi ben Chanina): The concern that the gentile switched it only applies to the gentiles own produce, but there's no concern that he had also received other boxes and they might have become switched with the Chaver's box.

If the Chaver deposited two boxes but the gentile only owns one box, the law is that (the first) one (received back from the gentile) is treated as Demai and (the second) one is definite Tevel.

This applies when both boxes still exist, but if the first was eaten, the second is Demai.

If one hundred people had each deposited a Se'ah with the gentile at the same time, when each person takes his back, he must separate as Demai.

If they then gave them all to one person, one after another, each of the hundred are now Demai.

If one person took back several Se'ah at the same time, the first is Demai and the rest is definite. If the gentile gave them to 100 people at the same time (since one is definite Tevel and the other 99 are doubtful - meaning Demai), we are concerned about each of those 100 people that they have the definite Tevel.

Question (Baraisa citing R. Shimon citing R. Tarfon): They treated the produce of this Jew who gave them (to the gentile) as Demai...?

Answer: The Baraisa didn't mean that all of the fruits are Demai; only the equivalent of his box, but the rest is definite Tevel.