156 GERM-CELL CYCLE IN ANIMALS 



This hypothesis is that pairs of oocytes unite end to 

 end, the posterior ob'cyte containing the keimbahn- 

 chromatin and the anterior furnishing the egg 

 nucleus. Stages in this process are shown in Fig. 47, 

 A,B,C, and D. 



As the oocytes increase in size and age the f ollicular 

 epithelium becomes gradually thinner and in several 

 instances only a delicate strand could be observed 

 between the ends of adjoining oocytes. In Fig. 47, A 

 two oocytes are shown without any cellular layer 

 between them, although the follicular epithelium 

 extends in a short distance at the point of contact. 

 The posterior cell is much the larger and older, and 

 possesses keimbahn-chromatin, but no nucleus. 

 The other oocyte is younger and smaller and con- 

 tains what has been interpreted as a disintegrating 

 spindle (s). The condition illustrated in Fig. 47, B 

 is similar except that the keimbahn-chromatin in 

 the posterior oocyte is less regular, having already 

 begun to break up, and the chromatin rods in the 

 anterior cell represent a further stage in the trans- 

 formation of a spindle into a nucleus. Figure 47, C 

 illustrates what is considered a later stage in the fusion 

 process. The anterior part, which contains a definite 

 nucleus, is connected with the posterior position 

 by a thick strand. The nuclear membrane is not 

 very distinct in the preparation indicating that the 

 nucleus is not yet completely formed. The posterior 

 part is not as large as in the other figures, since the 

 section was not exactly in the longitudinal axis, but 

 slightly oblique. The keimbahn-chromatin has been 



