138 



SEX IN MICROORGANISMS 



Fig. B. 



1-8, syngamy of Copromonas siibtilis, from Dobell (1908), redrawn. 1, early stage of 

 cell fusion; 2-5, formation of "reduction" nuclei, further progress of fusion; 6, 

 nuclear fushion in zygote; 7, 8, encystment accompanied by completion of nuclear 

 fusion. 9-15, "sexual" stages in Fhaciis pyrmn, from Krichenbauer (1937), redrawn. 

 9-12, fusion of a larger with a smaller nucleus; 12, enlarged nucleus with two endo- 

 somes; 13, "zygote" with "diakinesis" stage of nucleus; 14, first "meiotic" division; 

 15, after second "meiotic" division. 



