STKUCTURE AND DEVELOPMENT OF VERTEBRATE OVaRY. 397 



the stellate variety prodominates. The nuclei are sometimes in 

 very close contact, and sometimes separated by protoplasm, 

 which in many instances is very slightly granular. In a large 

 number of the nests nothing further is apparent than what 

 has just been described, but in a very considerable number 

 one or more nuclei are present, which exhibit a transi- 

 tional character between the ordinary stellate nuclei of my 

 second category, and the nuclei of permanent ova as above de- 

 scribed ; and in these nests the formation of permanent ova is 

 taking place. Permanent ova in the act of development are 

 indicated in my figures by the letters d o. Many of the inter- 

 mediate nuclei are more dt-finitely surrounded by granular proto- 

 plasm than the other nuclei of the nests, and accordingly have 

 their outlines more sharply defined. Between nuclei of this kind, 

 and others as large as those of the permanent ova, there are 

 numerous transitional forms. The larger ones frequently lie in a 

 mass of granular protoplasm projecting from the nest, and only 

 united with it by a neck (PI. XVIII, figs. 14 and 16). For 

 prominences of this kind to become independent ova, it is 

 only necessary for the neck to become broken through. Nests 

 in which such changes are taking place present various 

 characters. In some cases several nuclei belonging to a 

 nest appear to be undergoing conversion into permanent ova 

 at the same time. Such a case is figured on PI. XVill, 

 figs. 17 and 18. In these cases the amount of granular proto- 

 plasm in the nest and around each freshly formed ovum is small. 

 In the more usual cases only one or two permanent ova at the 

 utmost are formed at the same time, and in these instances 

 a considerable amount of granular protoplasm is present 

 around the nucleus of the developing permanent ovum. In 

 such instances it frequently happens several of the nuclei not 

 undergoing conversion appear to be in the process of absorption, 

 and give to the part of the nest in which they are contained a 

 very hazy and indistinct aspect (PI. XVIII, fig. 15). Their 

 appearance leads me to adopt the view that while some of the 

 nuclei of each nest are converted into the nuclei of the 

 permanent ova, others break down and are used as the pabu- 

 lum, at the expense of which the protoplasm of the young ovum 

 grows. 



It should, however, be stated, that after the outlines of the 

 permanent ova have become definitely established, I have oidy 

 observed in a single instance the inclusion of a nucleus within 

 an ovum (PI. XVIII, fig. 24). In many instances normal 

 nuclei of the germinal epithelium may be so observed within the 

 ovum. 



The nuclei which are becoming converted into the nuclei of 



