It becomes quite clear that Heidegger's interest in animality is less to determine its essential being, which he always seems to leave in suspense, but rather in the notion of "world," so that he might clarify the fundamental existential structure of Dasein as "being-in-the-world" through a comparative study. The very close reading of the relevant sections of the 29/30 course is clear and sober, and instead of propagating "heideggerese," clarifies it, cautiously examining and explaining every substantive claim in light of both Heidegger's overall project during these years and Uexküll's contribution (especially his notion of the Umwelt) to that project. I believe that these two chapters will (or should) become a standard secondary source for all those who want to question and understand Heidegger's analytic of animality and its relation to Dasein. That said, Buchanan at one point contends that those (like Lowith, Sartre, Jonas, and Merleau-Ponty, to name just a few) who have rued that Heidegger pays scant heed to the body in Being and Time would gain much from close attention to what he says of animal being. I am not yet quite convinced by that claim. Certainly they would gain something, but the human body and embodiment, is qualitatively different from animality, and this difference is not simply a function of the degree and kind of world that Dasein has and is in, and in which animals are poor. Heidegger is always a bit cagey, I think, about the exact nature of that difference, and while Being and Time may be, as some claim, a wholly new and ontological description of embodiment, Heidegger does leave the originary structure of the body itself -- animal and human -- in suspense.