1 82 J. THOMAS PATTERSON. 



In Fig. 9 is seen the last trace of the intracellular membrane 

 in a binucleated mass that is about ready to be freed from the 

 ovary. It is possible of course that the faint line about the 

 large nucleus is not an intra-cellular membrane, but only the 

 original cell-wall which has become much attenuated through 

 the absorption of yolk by the ovum. This figure is of further 

 interest in that it demonstrates with remarkable clearness the 

 manner in which the yolk is absorbed by the ova. At the ex- 

 treme end of the ovary the process is at its height, and one can 

 actually observe the configuration of the streams of food material 

 extending from the vitelline cells to the larger nucleus. This is 

 particularly true in the pseudopodial-like structure in the upper 

 median portion of the figure. On the extreme right, near the. 

 section of the tip of the second nucleus, the yolk cells are directly 

 open to the ova. It is not quite clear as to what extent the yolk 

 cells participate in the formation of the mass of yolk surrounding 

 the eggs, aside from merely giving up their nutritive materials; 

 but that they do assist in this formation is abundantly proved 

 in those capsules the yolk contents of which show many degen- 

 erating nuclei of vitelline cells. In some cases these fading 

 nuclei form a complete row just below the surface of the capsule. 



Some hall dozen cases have been found in which the ovum 

 apparently does not become surrounded by any considerable 

 amount of yolk, but after absorbing a small amount of food 

 material is set free from the ovary. These single naked eggs 

 float about in the parenchyma and probably never succeed in 

 producing embryos (Fig. 13). 



Some time prior to the liberation of the ova from the ovary and 

 the yolk-gland, the ovarian nuclei undergo marked changes. 

 During all of the preceding oogonial history the nucleus possesses 

 that characteristic coarse network of chromatin extending 

 throughout the nucleoplasm, and a very large, deeply staining 

 nucleolus (Fig. 9); but during the last stages of yolk absorption 

 the chromatin network becomes more or less indistinct (Fig. 7), 

 finally disappearing altogether, and in its stead a finely granular 

 condition of the chromatin appears. At the same time the 

 nucleolus stains less intensely and M>OII becomes very irregular 

 in < nitline (Fig. 10). 



