A new mishnah! If the blood from the animal spills on the floor instead of being collected, and only then it's collected, that offering is invalid. The Gemara delves into the verses that teach what is necessary - in terms of what needs to be accepted. Plus, positioning in slaughtering the animal, such that no blood should fall. Also, a dilemma: if the bowl used for collecting the blood drops out before the blood reaches the air space of the bowl, is that valid or not? The answer may be a parallel to a barrel used to collect water from a pipe that may later be used for purification (or not - does the lack of fitness for purification answer the bottomless bowl question, or not?).