ORIGIN OF DEFINITIVE SEX-CELLS 



463 



cords or cords of second proliferation. Sainmont ('05), von 

 Winiwarter and Sainmont ('08), d'Hollander ('04), and Firket 

 ('14). 



The majority of the cells in these lobulations are primordial 

 germ-cells, or rather oogonia, since active division has begun 

 and since they are in the direct ovuliferous line. They are not 

 related to the cells of the germinal epithelium in any way, be- 









med 



^:tQ,#. 



Fig. 7 Portion of a transverse section through embryonic ovary of a 9-day 

 chick. This drawing shows the germinal epithelium with dividing germ-cells; 

 these little nests of dividing primordial germ-cells give rise to the cortical cords 

 or cords of second proliferation. 



cause, in the first place there is no resemblance, secondly there 

 are no stages which are intermediate, and thirdly there are 

 present in the groups of oogonia, or primordial germ-cell de- 

 scendants, typical prismatic cells, which resemble in every way 

 cells of the germinal epithelium. 



Now to take up the first point more at length : The epithelial 

 cell is prismatic, long for its size, has a small nucleus, a sphere 

 that can hardly be demonstrated and mitochondria which are 



