OVUM IN THE CAPE AND NEW ZEALAND PBRIPATUS. 285 



Ovarian Ova. — Three ova of December are shown in 

 fig. 22, and are very similar to the September ones of 

 P. capensis; in fact, up till nearly the beginning of April, 

 the ova of the two species are indistinguishable. 



Fig. 23 is from a section of an ovum in which the germinal 

 vesicle has acquired the full size which it attains while still in 

 the centre of the ovum. The germinal vesicle has a somewhat 

 diflferent structure from that of P. ca pen sis of the same stage 

 (cf. fig. 8) ; it has a groundwork which has no structure, and 

 does not stain, but is fairly definitely marked off from the rest 

 of the egg, while in it lies a deeply-staining, irregular network, 

 which has a rather coarsely granular appearance, and a round 

 excentric large nucleolus, or germinal spot. Small round, 

 highly refractive yolky particles were present in the egg 

 protoplasm. 



The next ovum which I have figured is shown in fig. 24 ; 

 unfortunately it had become broken off from the ovary before 

 it was cut, so that I could not see its relation to its stalk or 

 follicle. It was round in shape ; it had a thick shell, which was 

 broken in one place, probably at the point of attachment to the 

 ovary. There was no trace of a germinal vesicle or germinal 

 spot. The protoplasm formed a loose reticulum with a granular 

 structure, and through it were scattered round homogeneous 

 bodies, which I believe to be yolk, but I have no observations 

 on their origin. 



Uterine Ova. — In the youngest ova in the uterus there is 

 no sign of germinal vesicle or male pronucleus. The proto- 

 plasm forms a loose reticulum and contains yolk-spheres. 



The reappearance of the germinal vesicle and the formation 

 from it of two polar bodies takes place as in P. cap en sis. 

 In two ova in which the formation of polar bodies was taking 

 place, the male pronucleus was present as a small chromatin 

 body lying at the periphery of the ovum opposite the side 

 where the germinal vesicle was situated, and surrounded by a 

 small zone of clearer, less deeply staining protoplasm than that 

 of the main part of the ovum ; this condition of the male pro- 

 nucleus is shown in fig. 21. There was no radiate arrange- 



