The 3 cases where "exempt" means not "no korban, but don't do it," but "no korban, and it's even allowed." Also: The new chapter of "8 crawling animals" - including discussion of what these creatures are, and the fact that wounding them leaves you exempt... Some significant disputes are these animals - what has separate skin? Plus: Killing a louse on Shabbat... How differently Chazal related to live, as compared to other animals, specifically with regard to their procreation (which we know today was not via spontaneous generation). Which, of course, raises questions of what to do when Chazal's halakhah is based on faulty science.