368 THE BIOLOGY OF STENTOR 



of kinetosomes into this area from, say, the nucleus or from any 

 other source, save that of the preexisting kinetosomes. In oral 

 primordium formation in ciliates in general, a disorganized 

 aggregation or " anarchic field " of additional kinetosomes appears 

 at the site of development. If these in fact arise from multiplication 

 of adjacent basal bodies of the lateral cilia, this would explain the 

 origin of the "building blocks" or structural components of 

 organelles. Yet, as Lwoff said, *' . . . if kinetosomes are necessary 

 for morphogenesis, they seem not to 'command' but to obey 

 some mysterious force which is responsible for their orientation". 

 The alignment and organization of kinetosomes into complex 

 structures and determination of what type of fibrous elaborations 

 these granules will produce thus implies an additional agency, a 

 pattern of "molecular ecologies" or of some preexisting ground 

 structure in the cortex. 



Working with Paramecium, Ehret and Powers (1959) have 

 challenged previous conceptions regarding the genetic continuity 

 of kinetosomes and the importance of fibrous networks in organiz- 

 ing the ciliate cortex. Briefly, they find that the cilia of the oral 

 primordium arise not from kinetosomes but from different entities 

 which might be "microsomes"; and they conceive the unit of 

 cortical structure as a ciliary corpuscle which usually bears one or 

 double cilia and associated elements, the close packing of these 

 spherules producing the appearance of hexagonal and rhomboidal 

 fibrous patterns. This interpretation is contrary to that of Yusa 

 (1957) and Roque (1956) who retain the postulate of the genetic 

 continuity of kinetosomes and agreement has not yet been reached, 

 yet the revolutionary conceptions of Ehret and Powers at least have 

 the merit of keeping the problems of ciliate morphogenesis in a 

 fruitfully flocculent state. The crowding of cortical granules, 

 apparently of internal origin, into every available space in the 

 ectoplasm of Stentor coeruleus would seem to offer a parallel to the 

 packing of ciliary corpuscles. But the unextensible, relatively thick 

 and solid ectoplasm of forms such as Paramecium and Frontonia 

 may represent a special and peculiar evolutionary development 

 (Tartar, 1954) and, as these investigators grant, it remains to be 

 seen how far their intriguing ideas are applicable to other ciliates. 

 The orderly packing and morphogenetic control of corpuscular 

 units, even in Paramecium, would seem to require, as with 



