REDUCTION IN UNICELLULAR FORMS 279 



Which the germ-nuclei unite (Fig. 139). Whether a reduction in the 

 number of chromosomes occurs in these cases was not determined • 



B 



f 



D 



H 



Fig. 140. — Conjugation of Closteriutti. [Klehahn,] 



dkt^' f'^^'n ^J^^' ""'^"' ^°"' chromatophores. B. Chromatophores reduced to two. nuclei 

 distinct, a Fusion of the nuclei. D. First cleavage of tiie zygote. /.-. Resulting 2-cell stage 

 /-. becond cleavage. G. Resulting stage, each cell bi-nucleate. //. Separation of tl,e cells- 

 one 01 the nuclei in each enlarging to form the permanent nucleus, the other (probably reprd 

 senting a polar body) degenerating. ' 



1 Achnosphceriufu forms one of the most extreme known cases of in-iireeding; for the 

 gametes are sister-cells which immediately reunite after forming the polar bodies. The 

 general facts are as follows : The mother animal, containing verv numerous nuclei, l>ecomes 

 encysted, and a very large number of the nuclei degenerate. TJie bodv then segments into 



