30 MORPHOGENESIS IN CILIATES 



could be a question of environment. But there is of course 

 a possibility that for kinetosomes, as for cells of higher or- 

 ganisms, there is an antagonism between multiplication and 

 other specific activities, that is to say, an antagonism be- 

 tween the synthesis of ^'kinetosomal substance" and syn- 

 thesis of ciliary substance. It is nevertheless possible to 

 consider as certain that formation of cilia depends on the 

 presence of one or more specific substance or substances, 

 and also that environment controls the maintenance of 

 cilia as it controls their formation. 



It has been shown that, at the end of tomitogenesis, all 

 the cilia-bearing kinetosomes divide, and the daughter 

 granule produces a trichocyst. Kinetosomes may thus di- 

 vide unequally: one of the granules remaining a kineto- 

 some, the other producing a trichocyst or a trichite. It 

 seems that the trichocystosome itself becomes a part of the 

 trichocyst. Nevertheless, once a trichocystosome has ex- 

 pressed its prospective potencies, that is to say, the forma- 

 tion of a trichocyst, it is no longer endowed with self -repro- 

 ducibility. 



But before forming a specific product, the modified gran- 

 ule, the trichocystosome of the predivision phase of Poly- 

 spira, or the trichitosome of the trophont of Foettingeria, 

 may undergo one or more divisions. The trichocystosome 

 or the trichitosome is therefore, in some cases, able to live 

 and to multiply as such. 



Sewall Wright (1941), discussing some aspects of the 

 physiology of the gene, has reached the following conclu- 

 sion: ^'Differences in local conditions may bring about a 

 differential accumulation of metabolism products arising by 

 the interaction of cytoplasm, nuclear products, and the en- 

 vironment, and eventually bring about the elaboration of 

 new plasmagenes in the cytoplasm of some regions of the 

 organism. ... It may be concluded that while the proteins 

 of cytoplasm are probably autonomous with respect to basic 



