92 ^lORPHOGENESIS IN CILIATES 



"Life," Louis Pasteur has written, "is dominated by 

 asymmetrical actions. I even foresee that all living species 

 in their structures, in their external forms, are primordially 

 functions of the cosmic dissymmetry." 



The problems of the physicochemical aspects of organiza- 

 tion and of asymmetry have been extensively discussed by 

 E. Faure-Fremiet (1943, 1948b) in suggestive reviews to 

 which the reader should refer. Faure-Fremiet has clearly 

 considered the possibility of protoplasmic dissymmetry as 

 the initial factor of orientation and has posed the question : 

 "Are the spatial properties of an organized system deter- 

 mined by the anisotropic properties of molecules, or is the 

 orientation of molecular structure controlled by distinct 

 organizational factors?" The cell is a collection of mole- 

 cules — micelles and organelles. The environment of a par- 

 ticle is essentially the sum of other particles, and one can 

 question whether their spatial distribution, which is organ- 

 ization, is not the result of the interaction of the particles 

 themselves. The morphogenetical field would be the reflec- 

 tion of the properties and relative number of these particles. 

 Orienting forces would be the interplay of asymmetrical 

 molecules. 



For example, the peritrichous ciliate Trichodina domer- 

 guei possesses a circular adhesive organ. This organ is 

 formed of articulated skeletal pieces of protein nature. After 

 the division, a new ring is formed. The skeletal proteins 

 are organized in a localized zone which behaves, according 

 to E. Faure-Fremiet and J. Thaureaux (1944), as a poly- 

 merization zone. In the formation of skeletal pieces, there 

 is a given orientation, a given direction, an asymmetrical 

 increase, the result of which is a specific organic structure. 

 The properties of such a polymerization zone are those of a 

 morphogenetic field. 



The mechanist is intimately convinced that a precise 

 knowledge of the chemical constitution, structure, and 

 properties of the various organelles of a cell will solve bio- 



