34 THE BIOLOGY OF STENTOR 



From the complexity of its structure we appreciate that the 

 formation of the membranellar band is indeed an astonishing 

 achievement of differentiation, involving multiplication of ciliary 

 basal bodies to 15,000 (judging from the data of Randall and 

 Jackson), the precise alignment of these bodies in rows and the 

 grouping of these rows by twos or threes, outgrowth of long cilia 

 from these granules, ingrowth of ciliary rootlets and their precise 

 association into triangular plates ending in a fiber, together with 

 the elaboration of the basal fiber connecting the end fibers, not to 

 mention the coiling and shifting of the entire structure to the 

 anterior end. All this occurs within about 4 hours. The perform- 

 ance is the more remarkable in view of the fact that when the 

 membranellar band is forming it can be slashed through many 

 times with a glass needle without producing any apparent abnor- 

 mality of construction (Tartar, 1957c). 



(d) Gullet 



The membranellar band continues in a sharply spiraled course 

 down into the gullet, as does the ectoplasmic striping which lines 

 the oral pouch and is itself continuous with the stripes of the frontal 

 field. Opening into the right-hand side of the oral pouch, the gullet 

 shows a double spiraling: as a pendant tube it takes about one 

 complete turn as it penetrates into the endoplasm, while the wall 

 of the gullet is itself under sharp torsion. Dierks claimed that the 

 opening into the gullet is capable of closure, though no one else 

 has observed this. 



In everted gullets of coeruleus Andrews (1946) saw the membran- 

 ellar band extending in a spiral to the lower end of the gullet, 

 while decreasing to half its usual width (Fig. 6a). In polymorphus, 

 Randall and Jackson describe the membranelles in this region 

 as bi- instead of tri-lamellar. In pigmented species the appearance 

 is often that only one side of the gullet is colored because the band 

 of membranelles is itself unpigmented. However, Dierks main- 

 tained, apparently erroneously, that the membranellar band does 

 not continue into the gullet. In any case, the gullet has its own 

 specialized ciliation. Gelei (1925) found that the ciUa here stained 

 differently, and he likened them to the pharyngeal cilia of turbel- 

 larian worms which serve in swallowing. Dierks even denied that 

 the kinetics of the frontal field continue into the gullet, being 



