A new mishnah focused in the kohen's washing of hands and feet, and immersing in the mikveh (10 and 5 times, respectively). With measures in place to preserve his modesty, of course. Which brings us to a dispute between Ben Zoma and R. Yehudah, with regard to how close to a risk of incurring later this washing avoids. What are they actually disagreeing about? Whether the washing (or lack thereof) invalidates the service itself. And how it increases the kedushah of his activity. Plus a distinction made between the first dunking and washing of the day, though the mishnah (and Ben Zoma and R. Yehudah) do not make that distinction explicit.