1^ DUBLIN 



center of the ovary and finally pass through the oviduct into the 

 brood-pouch formed in the lower portion of the atrium. 



As in the Copepod ovary, a continuous line of development 

 of the germ-cells can be traced from the center outward. We 

 accordingly find nearest the oviduct the smallest primary germ- 

 cells, which have persisted unchanged from the early stages of 

 the polyp. In these, division figures are never observed, except 

 in the youngest individuals. It may, therefore, be inferred that 

 the cells do not develop simultaneously. The nuclei, which 

 take up the greater part of the cell, are in the resting stage, the 

 chromatin being widely distributed in the form of a reticulum. 

 There are also at opposite ends of the nucleus two small nucleoli 

 which often move toward the center and fuse into one larger and 

 more irregular body. Altogether these cells are comparable to 

 those described by Hacker, '95, in the ovary of Canthocampt2is 

 as the primitive ^gg cells {Ureizellen), and as this author states, 

 " are to be considered as the direct descendants of the primary 

 germ-cells of the embryo, and through active, apparently perio- 

 dic, divisions, give rise to the elements of the ovary." 



Next in order come the oogonia (Text-fig. II, oog.). These, 

 as in other forms, pass through several generations and division- 

 figures are common both in young and in older ovaries. Dis- 

 regarding for the moment the last generation of oogonia (more 

 fully described below), the other generations are in the main very 

 much alike with but slight differences in size, the cells becom- 

 ing smaller with the successive divisions, although there is a con- 

 siderable growth period between these. The divisions of these 

 oogonia are important for a comparison with the subsequent proc- 

 esses. Fig. 62 shows a cross-section of a metaphase of an early 

 generation. The chromosomes are as was observed in the early 

 spermatogonia slender, distinctly V-shaped bodies, with the 

 angle toward the spindle. Fig. 6^ shows a longitudinal sec- 

 tion through a similar spindle. The 22 chromosomes are here 

 again V-shaped, and as such, they move tow^ard their two re- 

 spective centers where they concentrate into a very compact 

 deep staining mass (Fig. 64). 



The most important of the oogonial divisions is, however, 



