FINE STRUCTURE 49 



previously found only in certain plants, which is phototoxic to 

 herbivores. These tests by Moller showed that the pigments 

 which may comprise stentorin apparently belong to the mesonaph- 

 thodianthrone group of compounds also including the photo- 

 dynamic pigments hypericin and phagopyrin. The function of 

 pigments in coeruleus is still unknown. Like the apparently related 

 chromatic substances of niger they may render these stentors 

 sensitive to light. Alternatively or in addition, if the pigment in 

 igneus is the same as that in Blepharisma which Giese (1949) found 

 to be toxic to certain other protozoa, and if that of at least certain 

 if not all races of coeruleus and niger be phototoxic to some 

 predators as eaten, then stentor pigments might have some 

 protective value for their bearers. 



(c) Clear stripes and their fiber systems 



In the living animal the highly differentiated clear stripes show 

 a row of cilia on their left margin and in the center a wide, sub- 

 pellicular band best revealed by polarized light or phase micro- 

 scopy. This band doubtless represents the original " Muskelfaser " 

 described by Lieberkuhn in 1857. Later students of this minute 

 structure (notably Schuberg, 1890; Johnson, 1893; Nerescheimer, 

 1903; Schroder, 1907; Dierks, 1926a; and Gelei, 1926) published 

 varying accounts of its precise nature which are now rendered 

 obsolete by recent studies with electron microscopy. Earlier 

 accounts agree, however, that these bands run the length of the 

 animal, branch and rebranch in correspondence with the clear 

 stripes, are tapered toward the anterior end but much thickened 

 posteriorly, in cross-section appearing pendent from the pellicle 

 adjacent to the ciliary rows as shown in Fig. loc, being contractile 

 in function and hence deserving the name myoneme. The 

 possibility of fiber connectives between the basal granules of the 

 cilia, presumably required for their coordinated movement and 

 universally found in ciliates through subsequent study of silver- 

 line and infraciliature systems, was completely neglected. 



After the strained efforts with light microscopy, the EM studies 

 come as a revelation, though partially anticipated by Gelei (1926). 

 To date, we have the reports of Faure-Fremiet and Rouiller (1955), 

 Randall (1956), Faure-Fremiet, Rouiller and Gauchery (1956) and 

 Randall and Jackson (1958). Fig. lOA attempts to combine in one 



