KINETOSOME AS A VISIBLE CYTOPLASMIC UNIT 5 



fection, disease, and specific cluMnical reactions, and, of 

 course, in some cases the control of electron microscopy. 

 No identified chemical reaction has l)een ascribed to any 

 plasmagene. How can we obtain a picture of the activity 

 of plasmagenes? The situation seems difficult to say the 

 least. But Nature does not like to be disregarded and rarely 

 forgives classifications. Among these ''undefined residues 

 of heredity" which are considered as invisible are perfectly 

 visible granules, cytoplasmic, specific, self-reproducing vis- 

 ible granules. 



Thus we can approach directly the study of molecular 

 ecology. It is of course very advantageous to deal with in- 

 visible particles. We may organize them at will without 

 apparent danger. But w^hat will happen to the theory, 

 when, by chance, we are dealing with real visible granules, 

 the life history of which we are able to analyze? As will be 

 seen very soon, we are today in a position to perform this 

 analysis. Thus, we will find that, although molecular ecol- 

 ogy is a very clear, almost schematic, and very clever the- 

 oretical conception, it is nevertheless in excellent agreement 

 with the facts. Such abnormal events happen from time 

 to time. If Nature rarely forgives classification, she some- 

 times forgives theories. 



In all animals or plants, at the base of each flagellum or 

 cilium, one sees a spherical corpuscle. These corpuscles 

 always reproduce themselves by division. They are "self- 

 reproducing" systems, and obviously cytoplasmic. Shall we 

 refer to them as "undefined residues of heredity" or as plas- 

 magenes? Why should we? Let us simply call them by 

 their name: "blepharoplasts" or "kinetosomes," and let us 

 first say a few words about the way protozoologists consider 

 these kinetosomes. 



During cell division, a granule is present in the center of 

 the aster, which is the centriole or central body. When 

 spermiogenesis proceeds, the flagella arise from this cen- 

 triole. The centriole of animal cells is a lineal descendant 



