THE URINOGENITAL SYSTEM. 351 



of the size of the cell), they contain two nucleoli (PI. 12, figs. 14.6- 

 and 14^), and are at times so lobed as to give an apparent 

 indication of commencing division. 



A multi-nucleolar condition of the nuclei, like that figured 

 by Gotte 1 , does not appear till near the close of embryonic 

 life, and is then found equally in the large ova and in those not 

 larger than the ova which exist at this early date. 



As regards the relation of the primitive ova to each other 

 and the neighbouring cells, there are a few points which deserve 

 attention. In the first place, the ova are, as a rule, collected in 

 masses at particular points, and not distributed uniformly (fig. 

 14 a). The masses in some cases appear as if they had resulted 

 from the division of one primitive ovum, but can hardly be 

 adduced as instances of a commencing coalescence ; since if the 

 ova thus aggregated were to coalesce, an ovum would be produced 

 of a very much greater size than any which is found during the 

 early stages. Though at this stage no indication is present of 

 such a coalescence of cells to form ova as is believed to take 

 place by Gotte, still the origin of the primitive ova is not quite 

 clear. One would naturally expect to find a great number of 

 cells intermediate between primitive ova and ordinary columnar 

 cells. Cells which may be intermediate are no doubt found, but 

 not nearly so frequently as might have been anticipated. One 

 or two cells are shewn in PI. 12, fig. 14 a, x, which are perhaps 

 of an intermediate character ; but in most sections it is not 

 possible to satisfy oneself that any such intermediate cells are 

 present. 



In one case what appeared to be an intermediate cell was 

 measured, and presented a diameter of - oi2 Mm. while its 

 nucleus was *oo8 Mm. Apart from certain features of the 

 nucleus, which at this stage are hardly very marked, the easiest 

 method of distinguishing a primitive ovum from an adjacent 

 cell is the presence of a large quantity of protoplasm around 

 the nucleus. The nucleus of one of the smallest primitive ova 

 is not larger than the nucleus of an ordinary cell (being about 

 008 Mm. in both). It is perhaps the similarity in the size of 

 the nuclei which renders it difficult at first to distinguish de- 

 veloping primitive ova from ordinary cells. Except with the 

 1 Entwickhmgsgeschichte der Unfa, PI. i, fig. 8. 



