366 THE BIOLOGY OF STENTOR 



may be evident in Blepharisma in which the present feeding 

 organelles induce not primordia but sites for primordia. The 

 eventual evolutionary development therefore provides a cell cortex 

 with a persisting pattern and polarity (not labile as in flagellates) 

 as well as semiautonomous units of ectoplasmic structure whose 

 organization is apparently controlled by that pattern. Possibly the 

 greatest persistence and fixity of cortical pattern is to be found in 

 Paramecium, which cannot remodel a defective pattern as stentors 

 do and rounds out the contour of the cell after an end has been cut 

 off only by subsequent feeding and structural growth (Tartar, 



1954)- 



2. Hypotheses concerning morphogenesis of ciliates 



A cortical pattern in ciliates is best revealed by silver staining. 

 By this method Klein showed that the surface of ciliates presents 

 a network in orderly relation to which are found the ciliary 

 kinetosomes, oral structures, and other ectoplasmic organelles. 

 Certain fibers, as others had suggested, are probably concerned 

 with the coordination of ciliary organelles in swimming, searching, 

 and feeding behavior. But Klein (1932) also conceived that the 

 ground network might produce the ciliary and other organelles or 

 at least guide their organization into specific patterns. Many have 

 differed with Klein, on the grounds that certain of his networks are 

 mere sculpturings in a " dead " pellicle and hence are an end result 

 rather than a possible cause of morphogenesis, as well as that fibers 

 do not produce kinetosomes but the reverse. Klein's work has 

 therefore been much neglected because of these differences of 

 interpretation, though Gelei (1936) made notable contributions in 

 a similar approach. Yet the idea of some cortical pattern which, as 

 a continuum, affords the basis for integrating all ectoplasmic 

 differentiation and, as a geometric scaffolding, provides for their 

 orderly deployment has endured because it fulfils a logical 

 requirement. 



In Faure-Fremiet's (1950,1954) conception, there is a basic 

 cortical pattern but it is on a finer level and consists in the orienta- 

 tion and association of molecules in orderly arrangements. We are 

 therefore provided a link with the biochemical basis of the 

 organism, structure being successively compounded on pre- 

 existing structure until the visible form and differentiation of the 



