THE OVUM OF THE NINE-BANDED ARMADILLO. IOI 



1. On the basis of a cytological examination of one pair of 

 ovaries Rosner ('01) concluded that four adjacent follicles fuse 

 in such a way that four eggs are thrown into a single follicular 

 cavity; on the rupture of this compound follicle four eggs are 

 discharged simultaneously, descend the fallopian tube held 

 together in a mass by means of their discus proligerus cells, 

 become fertilized, undergo cleavage and come to a common 

 point of attachment in the uterus; subsequently the contiguous 

 walls of the four blastocysts atrophy and a single vesicular chorion 

 is produced. According to Rosner then polyembryony does not 

 exist, but merely the appearance of polyembryony, due to an 

 early fusion of four blastodermic vesicles. 



2. It has been suggested that the ovum might give off two 

 large polar bodies and that the first of these might divide, thus 

 producing four potential ova within one zona. These would be 

 separately fertilized and would produce a morula apparently 

 simple but actually quadruple. Subsequently the four embryonic 

 components would segregate themselves and produce the quad- 

 ruplets. This view also denies the reality of polyembryony. 



3. There might occur an early fusion of four ovogonia or 

 ovocytes to form a tetra-nuclear germ cell, which would be 

 fertilized by as many spermatozoa as there were female pro- 

 nuclei and thus give rise to a quadruple embryonic vesicle. 



4. The two maturations might occur within the cytoplasm of 

 the egg, without the extrusion of polar bodies. We would have in 

 this case an egg with four pronuclei which, when fertilized with 

 four spermatozoa, would be able, conceivably, to produce four 

 embryos. 



5. There might occur two successive parthenogenetic divisions 

 of the female pronucleus, prior to fertilization, which would 

 require four spermatozoa for their fertilization and would thus 

 account for the observed conditions. 



6. The cytoplasmic materials of the ovum might be physio- 

 logically isolated into quarters during some period of the ovarian 

 history. Such a condition might conceivably foreshadow the 

 actual isolacion of embryonic primordia as it occurs at a fairly 

 early period of embryonic development. 



7. The cause of specific polyembryony may lie in factors 



