John P. Munson 331 



the chloroform comes in contact with them, break up into innumerable 

 tiny droplets, that go spinning in all directions, setting up strong cur- 

 rents in the Avhole mass. In this way these bodies all disappear. I take 

 this to be somewhat similar to an emulsion, and the white globules to 

 be of a fatty or oily nature. It is doubtless the chloroform in the 

 ordinary process of imbedding, possibly also the heated paraffine which 

 is responsible for the absence of these globules in the mounted speci- 

 mens. 



The true yolk-spheres differ from these globules in being homogene- 

 ous throughout (Plate VII, Fig. 100). Others, slightly smaller, are 

 finely granular (Plate VII, Fig. 99), while still smaller ones are coarsely 

 granular (Plate VII, Fig. 101). Comparing the yolk-bodies in the 

 order of their size, as Figs. 98, 99, 100, 101, it appears that the inner 

 granules grow smaller as the yolk-spheres grow larger, till the homo- 

 geneous state is attained in the larger spheres. This might be taken 

 to mean that the same sphere changes in this respect as it grows, were 

 it not for the fact that many of the smaller spheres are as homogeneous 

 as the largest, a fact which may mean that there are specific differences 

 between the various spheres throughout their entire history. 



The egg-membrane consists of an outer homogeneous layer which 

 when torn has a fibrous appearance. Within this outer layer there is 

 another one having radial striations (Plate VII, Figs. 84, 85, 86, 87). 

 Surrounding the egg-membrane are the follicle cells forming a compact 

 single layer of approximately equal cells (Plate I, Figs. 1, 2). 



As the egg grows, it pushes out more and more from the germinal 

 ridge, and becomes surrounded by a second and a third epithelial layer 

 (Plate I, Figs. 1, 2). The second of these seems to be the original 

 stroma cells surrounding the oogonia within the ridge. It remains 

 quite closely applied to the follicle cells, but seems not to be organically 

 connected with the follicle. This epithelial tunic, as well as the third 

 or outer tunic, is richly supplied with blood-vessels. The third or 

 outer tunic is more loosely applied, forming a loose bag, as it were, 

 around the egg. It arises evidently from the peritoneal part of the 

 stroma of the germinal ridge. When the egg is discharged from the 

 ovary, it enters this outer bag, which serves to convey it to the oviduct. 



On the Organization of the Egg. 



Throughout the entire history of this egg, both the nucleus and cyto- 

 plasm exist. At first the cytoplasm is very much reduced, being appar- 

 ently little more than an attraction sphere with archoplasm extending 



