198 



liEDUCTION OF THE CHROMOSOMES 



E. Reduction in Unicellular Forms 



A reduction of the number of chromosomes as a preparation for 

 conjugation in the one-celled forms has not yet been certainly deter- 

 mined, but there are many facts that render it highly probable. In 



B 



C 



D 



E 



H 



Fig. 99. — Conjugation of Closteriitm. [Klebahn.] 

 A. Soon after union, four chromatophores. B. Chromatophores leduced to two, nuclei 

 distinct. C. Fusion of the nuclei. D. First cleavage of the zygote. E. Rrsulting 2-cell stage. 

 /•: Second cleavage. G. Resulting stage, each cell bi-nuoleate. H. Separation of the cells; 

 one of the nuclei in each enlarging to form the permanent nucleus, the other (proliably repre- 

 senting a polar body) degenerating. 



