CYTOPLASMIC INHERITANCE 27-12 



Present evidence strongly supports the view that the Kappa sub- 

 stance is a virus which is widely established in the genus because it 

 confers a selective advantage upon the infected individual by caus- 

 ing the death of others competing for the same food. Individuals 

 carrying the K gene are susceptible to Kappa which the kk indivi- 

 duals are immune. The term "plasmagene" has implications of 

 origin involved in Darlington's definition, and the evidence produced 

 by Sonneborn's study of Klappa does not identify it as a plasmagene 

 nor distinguish it from a virus. The Feulgen -positive structures 

 in the cytoplasm of paramecia carrying Kappa which Dr. Freer ex- 

 hibited at the A.A.A.S. demonstrations in Washington, 1948, resemble 

 rickettsias closely. I consider this demonstration a confirmation 

 of my earlier views that Kappa is a parasite which gives the infect- 

 ed organisms an advantage by killing their competitors rather than 

 themselves. 



C. Antigenic Plasmagenes in Paramecium 



Sonneborn has described a phenomenon in Paramecium invol- 

 ving maternal inheritance of antigens which he considers similar 

 to the maternal inheritance of Blappa. However, maternal inheri- 

 tance of antigens in Paramecium appears to be a different pheno- 

 menon from the transmission of Kappa substance and more directly 

 related to the mechanism of gene action than the Kappa phenomenon. 

 A Paramecium with an antigenic constitution A can be transformed 

 into one with an antigenic constitution B by treatment with anti A 

 serum. B can in turn be transformed into C by treatment with 

 anti B serum and in this manner a variety of different Paramecia 

 are produced. At least one of the antigens has been demonstrated 

 to be gene -dependent. The variety of different types is produced 

 (according to Sonneborn's hypothesis) by the reduction in the 

 amounts of competing autonomous cytoplasmic plamagenes. He 

 has not distinguished these plasmagenes from the Kappa substance. 

 However, since the Kappa substance is the only one which 

 can be demonstrated by the Feulgen technique it is obviously a 

 unique form and the only thing in common between the antigens 

 and the Kappa substance is the fact that their transmission is 

 controlled to a large extent by maternal inheritance. The excon- 

 jugant which originally contained a specific antigenic characteris- 

 tic produces offspring with this same antigen. 



D. Adaptive Fnzyme Formation 



Spiegelman (1946) uses a variation of the plasmagene hypothe- 

 sis to explain the phenomenon of adaptative fermentation in yeast. 

 Unfortunately, he uses the same word which Darlington coined and 



