INTERACTIONS OF MORPHOOENETIC UNITS 81 



relations of sucli an ''orienting system" to the oriented 

 material? 



If something orientates kinetosomes, it can bo only by 

 virtue of some electronic or intermolecular forces. Let us 

 admit the hypothesis that the orienting system of an adult 

 ciliate is a rigid structure, unable to grow beyond certain 

 limits, as are the meshes of the cortical network. If the 

 kinetosomes continue to increase in number, the "reactive 

 groups" of the orienting system will finally become ''satu- 

 rated." The newly formed kinetosomes will find no place 

 to attach themselves. Their position will no longer be 

 controlled. 



But if kinetosomes are normally bound to the orienting 

 system by electronic forces, this means that they have also 

 "reactive groups." Kinetosomes which are not bound to 

 the orienting system have ipso facto "non-saturated bonds" 

 able to attract or to aggregate free building blocks of the 

 orienting system. The free blocks would result from con- 

 tinued synthesis after the size limit of the orienting system 

 was reached. These blocks will now crystallize according 

 to their structure and environment and form new systems 

 or new organelles. We can propose as an example of this 

 type of phenomenon the attracting and orienting action of 

 the kinetosome in so many metazoan cells or Protozoa. 

 Certainly if one kinetosome is able to exert such an influ- 

 ence, groups of kinetosomes may have also a pow^erful 

 action. 



In ciliates it is certain that multiplication of kinetosomes 

 precedes organization. The oral system, the membranelles 

 of Leucophrys or of Licnophora, are modelled in anarchic 

 kinetosomal fields. The cortical network of Euplotes is 

 formed around the newly formed fields of kinetosomes 

 which will produce the cirri. Strangely enough, the corti- 

 cal network of the ventral face of Euplotes develops sepa- 

 rately around the eight newdy formed cirri. There is not 

 one morphogenetic field for each daughter cell, but a series 



