In the previous parts of this daf we learned that R. Meir forbids one from using something that is alive as the wall of a sukkah (and from other uses as well). Abaye said that R. Meir is concerned lest the animal die, whereas R. Judah who allows an animal to be used as a wall for a sukkah is not concerned that death will happen so soon.
In today’s section the Talmud cites another passage where Abaye seems to say the opposite—R. Meir is not concerned about death occurring, whereas R. Judah is.
The Talmud will now cite a few tannaitic sources and a statement by Abaye in which he explains their contradiction. The first mishnah brought describes an Israelite woman who is not allowed to eat terumah unless she was married to a priest (Kohen). If she is married to him she can eat terumah as long as he is alive. If he goes abroad she can continue to eat terumah assuming that he is still alive. Thus this mishnah is not concerned about death.
In this mishnah a husband gives his wife a conditional get. The get will go into effect one hour before he dies. The reason that one would want to do such a thing is that if he divorces her before he dies she will not be liable for levirate marriage (marriage to his brother). If the husband is a kohen, she immediately cannot eat terumah because we must be concerned that he might die at any moment. Thus in this mishnah we are concerned with death.
Abaye solves the contradiction between these two mishnayot by saying that the first mishnah follows R. Meir who is not concerned with death and the second mishnah follows R. Judah who is concerned with death. Here we can see the contradiction with the previous passage—Abaye here contradicts what he said above.
Abaye’s prooftext that R. Meir is not concerned with death and R. Judah is concerned with death comes from a baraita dealing with a completely separate matter. If a person buys wine from a Samaritan who does not tithe he will need to separate tithes and terumah before he drinks the wine. In this case he is traveling with the wine and Shabbat comes, which means he can’t drink without separating first tithes and terumah (one can eat produce without tithing under certain circumstances, but once Shabbat comes it must be tithed). He also doesn’t have a pure jug in which to put the terumah. So what he does is declare that in the future he will separate terumah and the appropriate tithes. This separationis valid according to R. Meir and he may now drink the wine. Rabbi Judah and R. Shimon do not allow this, lest the wineskin split and he wouldn’t be able to tithe later on and it turns out that he drank untithed wine.
In conclusion, we can see from this baraita that R. Meir is the worrywart whereas R. Judah is not. This is indeed opposite from Abaye’s explanation of the sukkah mishnah, where R. Meir was concerned lest the animal died and R. Judah was not.