CILIATES 203 



oral anlage formation, and if these are laterally adjoined in the 

 wrong sense (though homopolar), the induced adoral zone of 

 membranelles will spiral in the wrong direction and produce no 

 mouth or an unusable one. The significance of spatial relation- 

 ships here — lateral distances between kineties — is harder to 

 relate to the ultrastructural picture than is the significance of 

 polarity and asymmetry. But Stentor is relatively a huge organism, 

 and efforts to compare broad- and narrow-stripe zones in electron 

 micrographs have not been made. 



Other heterotrichs that have been examined in somewhat less 

 detail or at less high resolution include Spirostomum (Finley, 1951, 

 1955; Randall, 1956, 1957; Pautard, 1959a, 1959b; Finley and 

 Brown, 1960; Inaba, 1960), Blepharisma (Inaba, Nakamura, and 

 Yamaguchi, 1958), Condylostoma (Yagiu and Shigenaka, 1958a, 

 1958b, 1958c, 1959a, 1959b) and Nyctotherus (King, Beams, 

 Tahmisian, and Devine, 1961). Spirostomum and Bkpharisma are 

 placed in the same family and are rather similar in morphology. 

 Both have laminated kinetodesma like those of Stentor, although 

 details of the connection with kinetosomes are not available. 

 Spirostomum is strongly contractile — though not so extensile as 

 Stentor — while Bkpharisma is very slightly so at best. Neither is 

 reported to possess the endoplasmic M-bands of Stentor. 



The pigment granules that give Bkpharisma undulans its charac- 

 teristic pink color are spheroidal bodies about 0-5 \x in diameter, 

 limited by double membranes and filled with a finely granular 

 material of moderate density. They are neatly layered immediately 

 beneath the pellicle. A colorless strain lacks such granules but 

 has instead abundant, smaller, very dense, irregular granules in a 

 corresponding position. 



Condylostoma has two limiting membranes over an ectoplasmic 

 zone of packed vacuoles, some of which may be identifiable as 

 mucigenic bodies. This zone occupies longitudinal ridges 

 separating the furrows in which lie the kineties. Transverse 

 furrows may also be present, but not consistently. The most 

 striking feature of the published micrographs of Condylostoma is 

 the presence of laminated fibrillar kinetodesma identical to those 

 of Stentor. As in Stentor, the origin of individual fibrils at kineto- 

 somes is very clear, as is their path to the right and posteriad from 

 the kinetosome. Some pictures suggest that several fibrils arise 



