SEX IN PROTOZOA 



141 



but in each case a rearrangement of sequences seems to indicate cell 

 division rather than cell fusion. Zederhauer (1904) showed association 

 of individuals of Ceratiwn himndinella in pairs with the extrusion and 

 fusion of protoplasts between the "parents" to produce a rounded 

 "zygospore" which encysted (Fig. C, 6 to 8). Development of the 



Fig. D. 



1-14, stages in sexual reproduction of Glenodiniwn lubiniensiforme, from Diwald 

 (1938), redrawn. 1-4, development of gametes; 5, escape of gametes; 6, 7, fusion of 

 gametes; 8, nuclear fusion; 9, encystment of zygote; 10, excystment of zygote; 11-12, 

 development of "swarmers"; 13, degeneration of two "swarmers"; 14, excysted 



