CHAPTER Z^ 



The Cortical Network of Suctorians; 

 Reproduction and Organization 



Adult suctorians are devoid of cilia. They feed by numer- 

 ous sucking extensions. The non-ciliated parent produces 

 a ciliated daughter organism generally referred to as an 

 embryo or bud. 



The origin of the cilia of the embryo in this group of 

 organisms was, for a very long time, one of the problems of 

 protozoology. It was solved by the study of Podophrya fixa 

 [E. Chatton, A. and M. Lwoff, and L. Tellier (1929)]. On 

 the surface of the adult are numerous kinetosomes which 

 are scattered all over an irregular network. The first sign 

 of reproduction is the multiplication of these granules in 

 one region of the adult. The kinetosomes become aligned 

 in regular rows, and the hitherto irregular network is now 

 formed, in this region only, of square units which are also 

 regularly aligned. Cilia are produced only by the kineto- 

 somes of this organized field. 



It is obvious that the kinetosomes of this region are sub- 

 mitted to conditions which induce their multiplication and 

 that some forces, or fibers, must arise which orientate the 

 network and the kinetosomes. 



A closely related species, Podophrija parasitica, has been 

 examined by E. Faure-Fremiet (1945b). It lives as para- 

 site on the surface of ciliates and also produces ciliated em- 

 bryos. However, when the host is exhausted, lines of kineto- 

 somes are formed, not only on one area, but all around the 

 suctorian, and cilia are produced. The adult as a whole is 

 thus transformed into a huge "embryo.'^ The change takes 



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