MEIOSIS 



207 



compacted into a tight knot. Presynizetic stages were passed 

 through rapidly and the nucleus now contained a biconvex 

 nucleolus, and closely adjacent to it lay a knot of chromatin 

 material. The transformation of the reticulum into a thread was 



O^ 



*# 



w 



o 





3 4 



Fig. 76. — Megaspore development in CEnothera ruhricalyx. 

 (1) Loosening of synizetic knot. The thread is connected with 

 a dark-staining body within the larger nucleolus. (2) The seg- 

 mented spireme can still be seen attached to the endonucleolus. 

 The knot is loosening and several pairs of chromosomes have 

 been set free. (.3) Diakinesis. The spireme is now resolved into 

 six chromosomes, arranged end-to-end and four bivalents. 

 (4) Microsporogenesis in CE. novce-scotice. Synizesis. Large 

 chromatin aggregations still persist. (1-3, After Gates and 

 Sheffield, Proc. Roy. Soc. (Lond.), 4, After Sheffield, Anns. Bot.) 



thus completed. The fine long thread was tightly tangled, but 

 was found to be attached to the endonucleolus (Fig. 76, 1). The 

 staining capacity of this thread rapidly increased, while that of 

 the nucleolus decreased. Synizesis was very prolonged and the 



