Nazir

Come and hear: Shammai says, even a single bone, from the backbone or from the skull [defiles by 'overshadowing']!  Shammai is different, for he takes the much more stringent view. Can we infer from this that Shammai's reason  is that he is strict, but according to the Rabbis [there is no defilement by overshadowing'] unless there is a half-kab of bones? — Perhaps the Rabbis only disagree with Shammai where there is a single bone, but where there is a quarter [kab] of bones even the Rabbis agree [that this is sufficient]. R. Eliezer said: The Elders of an earlier generation [were divided]. Some used to say that a half-kab of bones and a half-log of blood [is required] for everything,  whilst a quarter [-kab] of bones and a quarter [-log] of blood is not sufficient for anything. Others used to say that even a quarter [-kab] of bones and a quarter [-log] of blood [is enough] for everything. The Court that came after them said that a half-kab of bones and a half-log of blood [is the quantity] for [making unclean] everything, a quarter [-kab] of bones and a quarter [-log] of blood [is sufficient] in the case of terumah  and sacred meats,  but not in the case of a nazirite or one preparing the paschal lamb.  But surely the compromise of the third [opinion] IS no [true] compromise?  — R. Jacob b. Idi replied: They had it as a tradition deriving from Haggai, Zechariah and Malachi. ON ACCOUNT OF THESE A NAZIRITE MUST POLL: The word THESE,  in the first clause serves to exclude a barley-corn's bulk of bone, for touching or carrying which he must [poll] though not for overshadowing it — The word THESE in the next clause serves to exclude a rock overhanging a grave. OR A HALF-KAB OF BONES: