THE KINETOSOME IN DEVELOPMENT 89 



between the two daughter organelles the result of an in- 

 duced unequational division? The kinetosonie has been 

 considered as a "unit." The evidence for doing so is only 

 morpholooical. that is to say, largely insufficient. A kineto- 

 sonie is large enough to be a complex of different molecular 

 species, living together side by side and generally multiply- 

 ing together. But it is possible that some conditions may 

 favor one molecular species. The unequational division 

 would thus correspond to an induced division of one part of 

 the kinetosonie. We can also admit that, if owing to a 

 changed environment one molecular species has ''grown" 

 more than others, division might give rise to a 'Vlisequili- 

 brated" or modified particle. Things look like an induced 

 unequational division only if we consider the kinetosonie as 

 a "unit." 



3. But the possibility remains that kinetosomes and 

 trichocystosomes are in fact the product of a normal divi- 

 sion. Their different behavior could be due to different 

 factors : 



a. Owing to its position far from the kinetodesma, the 

 trichocystosome could be in slightly different environmental 

 conditions from the kinetosome. We know that mitochon- 

 dria, for example, are not equally distributed in the cortex 

 of a ciliate [E. Chatton and S. Brachon (1935)]. 



b. The kinetosome remains attached, probably by a fiber 

 to the kinetodesma. This fiber may perhaps modify some 

 of its properties. 



It is very difficult to make a choice among hypotheses 1, 

 2, and 3. It will be, in fact, impossible as long as the be- 

 havior of kinetosomes has not been submitted to an experi- 

 mental analysis. This should really be attempted. How- 

 ever, it must be recalled that in a flagellate such as Tricho- 

 monas one single kinetosome is able to give rise to a flagel- 

 lum, a fiber, an axostyle, and a parabasal body. These or- 

 ganelles may be chemically closely related, and it is possible 

 that their production corresponds to minute changes of the 



