240 



PROTOZOOLOGY 



ing among the killer Fi clones, shows segregation of sensitives and 

 killers in the ratio of a single gene difference. In the presence of 

 dominant gene K, kappa is maintained, but in recessive k homozy- 

 gotes, kappa cannot be maintained and any kappa carried over from 

 killers is rapidly lost. Thus it is evident, Sonneborn points out, that 

 the plasmagene kappa is dependent on gene K. 



Dipell (1948, 1950) found a number of killer mutants in variety 4. 



End oi- conjuqa+iorv.: Separated except at paroral cone. 

 Time until separation is completed 



More +h<m 

 3o min. 



KHIer Killer 

 Clone, clone 



kk+/c kk+a: 



Killer Sensitive 



e clone 

 KK+/C KK+* 



Killer Sensitive 

 clone clone 

 KK+/C KK 



Fig. 101. Diagram showing the effects of transfers of different amounts 

 of the cytoplasm between mates in conjugation of KK+ kappa killers 

 and KK sensitives in Paramecium aurelia (Sonneborn). 



She showed through breeding analysis that these mutations have 

 brought about no change in any gene affecting kappa or the killer 

 trait, but have been in every case due to changes in kappa. In a 

 mutant which was capable of producing two types of killing, there 

 were two kinds of kappa which she succeeded in separating in differ- 

 ent animals and their progeny. Thus it became apparent that kappa 

 can undergo mutation, that various mutant kappas can multiply in 

 animals with the original genome, and that the kappas are deter- 

 mined by themselves and not by nuclear genes. 



According to Preer (1948), the kappa particles (Fig. 102) in the 

 killer race G are about 0.4ju long, and those in a mutant Gml only 

 about 0.2-0.3ju long, while in other strains they measure as much as 



