KIXETOSOME AS A VISIBLE CYTOPLASMIC UNIT 7 



It is generally stated that the contriole of animal cells 

 may give rise to flagclla and behave like a ble]ihar()]:)]ast 

 or a kinetosome. According to E. Chatton (1924 and 1931), 

 this proposal must be inverted. The centriole is phylo- 

 genetically and primarily the organelle giving rise to the 

 fiagellum. It may, in some cases, participate in nuclear 

 division. Every centriole is a kinetosome, but every kineto- 

 some is not a centriole. 



The careful study of hundreds of flagellates has revealed 

 that the kinetosome is always formed by the division of a 

 pre-existing kinetosome. It is endowed with genetic con- 

 tinuity, and its existence has been demonstrated even in 

 non-motile stages of the life cycle. This kinetosome gives 

 rise to the fiagellum. It is able to multiply independently 

 of the nucleus, thus giving rise to chains of kinetosomes. 

 The careful study of numerous ciliates has shown that the 

 kinetosomes of ciliates are also endowed with genetic con- 

 tinuity. Even in forms which are devoid of cilia during a 

 long period of their life cycle, the kinetosomes may often 

 be seen organized, forming what we have called with E. 

 Chatton and M. Lwoff (1929) an ^^infraciliature." And the 

 kinetosomes of the ciliated "embryo" will be formed from 

 these pre-existing kinetosomes. But kinetosomes are not 

 only able to divide and to produce cilia. They are able to 

 secrete fibers, to give rise to other granules producing 

 trichocysts or trichites. 



They play a prominent role in development, differentia- 

 tion, and morphogenesis of ciliates. They move and vary 

 constantly. 



These cytoplasmic organelles, endowed with genetic con- 

 tinuity, live in a genetically constant system, thus providing 

 a beautiful model of a self-reproducing particle whose activ- 

 ity is controlled by its environment [c/. A. Lwoff (1949b)]. 



My intention is to study the behavior of kinetosomes 

 during the life cycle of some ciliates, to analyze and to dis- 

 cuss the various aspects of their movements and activity 



