46 MORPHOGENESIS IN CILIATES 



ditions may be different in different meridians, there is a 

 possibility that selection of mutated kinetosomes may take 

 place. Thus the possibility that different lines of kineto- 

 somes could be different cannot be excluded. A change in 

 the morphology of a ciliate could be the result of a new re- 

 sponse of populations of mutated kinetosomes to the same 

 environment. 



The work of T. Sonneborn and G. Beale (1949) has shown 

 that under the influence of antisera the antigenic type of 

 Paramecium is changed. An analysis of this phenomenon 

 has brought the authors to the conclusion that the antigenic 

 type was controlled by plasmagenes. Taking into account 

 the paralyzing effect of antisera, I have been led (1949a) 

 to the hypothesis that Sonneborn and Beale's antisera could 

 act on cilia. The responsible antigens would be ciliary anti- 

 gens. As cilia are produced by kinetosomes, these could 

 have a share of responsibility in the Sonneborn-Beale phe- 

 nomenon. The hypothesis according to which antiserum 

 could orientate the selection of kinetosomes or modify their 

 structure seems plausible. It is possible also that a sub- 

 stance analogous to the ciliary antigen could exist in the 

 kinetosome. Nevertheless, the problem of relations be- 

 tween the ciliary material and the kinetosome's constitu- 

 ents endowed with genetical continuity is posed by Sonne- 

 born and Beale's highly interesting experiments. This 

 problem of the natural or experimental selection of kineto- 

 somes remains one of the main problems of ciliate biology. 



According to V. Tartar (1941), "the ciliates present us 

 with a living fiber system having morphogenetic capacities." 

 Are we really entitled to speak of "living fibers"? Or to 

 consider that the visible cortical structure commands mor- 

 phogenesis? 



Tartar has cut Paramecium in such a way that the an- 

 terior part contained two nuclei but was devoid of oral 

 structure. These pieces never regenerated the mouth; "a 

 further evidence," writes Tartar, "of this rigid differentia- 



