MUSEUM OF CO:^IPARATIVE ZOOLOGY. 141 



m. The Ovarian Capsule. 



Plate H. Figs. 21-26. 



The epithelium of the ovarian capsule is not often easily made out in 

 ordinary stained preparations, for the nuclei of muscle fibres and con- 

 nective-tissue cells lie not only just external to the epithelial nuclei, 

 but frequently in the same plane with them. In most of ray prepara- 

 tions the boundaries of the epithelial cells cannot be seen at all, and I 

 have therefore confined my attention mainly to those which show them 

 distinctly. In shape, the cells are more or less irregular, oblong hexa- 

 gons (Figures 24 and 25 represent typical shapes). The cell walls are 

 broad and fibrillated, like those of the serosa, though the cells them- 

 selves are smaller even than those of the amnion. The nuclei are not 

 only larger in proportion to the cells, but often larger absolutely, than 

 the amniotic nuclei. The amount and arrangement of the chromatin 

 in the capsular nuclei (except in a certain phase) is almost precisely 

 like that already described for the nuclei of the amnion, but there is usu- 

 ally only one conspicuous nucleolus. The small amount of chromatic 

 substance, aside from the nucleolus, has a granular appearance, but 

 sometimes shows indications of a filamentous or reticular arrangement 

 (see Figs. 21, 23, 24). Seen in face view, the nuclei are circular, and 

 have a distinct nuclear membrane. The section (Fig. 2, nl. fol.) shows 

 that they are less flattened than the amniotic nuclei. 



Here, again, we have amitotic division, and of precisely the same 

 type as prevails in the amnion. Apparently, division is not of common 

 occurrence, for I have been able to find only a few^ instances, and have, 

 unfortunately, not seen its earliest stages. Figures 21, 22, and 23 show 

 the simple manner in which it is efi^ected. As each daughter nucleus 

 contains a nucleolus, and the ordinary resting nucleus has but one, 

 division of the nucleolus must precede division of the nucleus. In one 

 important respect the division of these nuclei differs from that of the 

 amniotic nuclei. The cell does not divide immediately after the nucleus, 

 and consequently a great number of cells are binucleate. Some even 

 contain three nuclei. I have obtained no evidence whatever of cell 

 division. 



