68 H. B. GOODRICH 



one of these plates giving a count of 40 chromosomes — the 

 microsomes are not visible and it is probable that the two large 

 paired chromosomes at the upper edge may be the two large 

 components of the X groups. 



2. The growth period and prophase. After a rest period simi- 

 lar to that found in the spermatogenesis the nuclei enter the 

 leptotene stage (fig. 23). This is preceded by a condition (fig. 

 22) showing parallel threads bearing paired granules but no 

 stage of a degree of concentration comparable to that found 

 in spermatogenesis (fig. 5) has been observed in oogenesis. 

 The processes of transformation of the leptotene to a pachytene 

 condition have been observed: 



a. Transition showing contraction or synzesis. Figure 25 shov/s 

 a contraction figure similar to that found in spermatogenesis 

 and this followed by an early pachytene condition (fig. 26) 

 showing heavy threads with no sign of duality except that they 

 occasionally they are attached to divergent fine threads. 



b. Transition not showing contraction. In this case the 

 threads thicken in some unanalyzable way (fig. 24) and pass 

 into the pachytene condition (fig. 27) which follows either mode 

 of transition. Although serial sections were made through this 

 section of the ovary no contraction figures vere found. The 

 first mode (a) of transformation was observed in the other arm 

 of the ovary of the same animal ; the whole ovary had been fixed 

 at one time in the same fixing bath of the Flemming-urea mixture. 



Figure 27 shows a late pachytene stage which already gives 

 a few signs of a longitudinal split of the threads. It will be 

 noted that the pachytene threads are at no time conspicuously 

 double as is in the case in spermatogenesis — the fusion of the 

 threads appears to have been more complete (assuming parasy- 

 napsis) . The strepsinema stage is not pronounced and the pachy- 

 tene nucleus changes to a diffuse condition (fig. 28) . The threads 

 lose their staining capacity and in a large part become massed 

 about the plasmasome, sometimes hiding it completely, and 

 showing irregular areas of greater concentration of chromatin 

 (fig. 29) . A few linin fibers traverse the nucleus and occasionally 

 paired granules may be observed upon them. The history of 

 the plasmosome is similar to that observed in spermatogenesis. 



