Niddah

Rabbah b. Shila citing R. Mattena who had it from Samuel stated: It once happened that a placenta was attributed to an embryo as late as  ten days [after the latter's birth].  [The law, however, that it] is to be attributed [to the existing embryo] applies only  where the expulsion of the placenta followed the birth of the embryo.  Rabbah b. Bar Hana citing R. Johanan stated: It once happened that a placenta was attributed to an embryo as late as  twenty-three days [after the birth of the latter]. 'You once told us', said R. Joseph to him, 'as late as twenty-four days'. R. Aha son of 'Awira citing R. Johanan  stated: It once happened that the birth of an embryo was delayed for thirty-three days after that of its predecessor. 'You', said R. Joseph to him, 'have in fact told us thirty-four days.' [Such an incident may be explained] satisfactorily according to him who holds that a woman who bears at nine months does not necessarily complete the full number,  since in such circumstances it is possible that the features of one embryo were completed at the end  of seven months  and those of the other at the beginning  of the ninth month,  but according to him who maintains that a woman who bears at nine months does complete the full number,  what can be said [in explanation of the incident]?  — Reverse the statements:  Thirty-three days in the case of the placenta  and twenty-three days in that of the embryo. R. Abin b. R. Adda citing R. Menahem of Kefar She'arim or, as some say, Beth She'arim, stated: It once happened that a child was born three months later than its predecessor and lo, both sit before us in the schoolhouse. And who are they? — Judah and Hezekiah the sons of R. Hiyya. But did not a Master say that a woman in conception cannot conceive again?  — Abaye replied: It was the same drop but it was divided in two sections; the features of one of these were completed at the beginning of the seventh month and those of the other were completed at the end of the ninth month. IF A PLACENTA IS WITHIN A HOUSE, THE HOUSE IS UNCLEAN. Our Rabbis taught: If a placenta is in a house, the house is unclean; not because a placenta is a child but because generally there can be no placenta with which there is no child; so R. Meir. R. Jose, R. Judah and R. Simeon regard [the house] as clean. 'Do you not agree', they said to R. Meir, 'that if it had been carried out in a bowl into an outer room it would be clean?' 'Indeed', he replied. 'But why?'  'Because it  is no longer in existence'. 'As', they retorted, 'it is not in existence in the outer room so is it not in existence in the inner room'.  'What was mashed once', he replied, 'is not like that which was mashed twice.' R. Papa once sat behind R. Bubi in the presence of R. Hamnuna and in the course of the session he observed: What is R. Simeon's reason?  He is of the opinion that any uncleanness with which anything of a different kind of uncleanness has been mixed is neutralized. Said R. Papa to them: 'Is this also the reason of R. Judah and R. Jose?'  They laughed at him. 'Is not this obvious', they said, 'why should there be any difference?'  — 'Even such a question',  said R. Papa, 'a man should submit to his Master  and not be content with silence;  for it is said, If thou hast done foolishly  thou art  lifting up thyself;  but  if thou hast planned devices,  lay thy hand upon thy mouth. R. Simeon  follows the view he expressed elsewhere. For it was taught: If some earth fell into a ladleful of corpse-mould [the latter remains] unclean, but R. Simeon holds it to be clean. What is R. Simeon's reason? — Raba  replied: 'I met the Rabbis of the schoolhouse while they were sitting at their studies and explaining that  it is impossible that [somewhere in the mixture] two particles of earth to one of the corpse-mould should not represent the larger portion, so that  something is missing',  and I said to them, 'On the contrary! It is impossible that [somewhere in the mixture] two particles of the corpse-mould should not represent a part greater than