226 ELECTRON-MICROSCOPIC STRUCTURE OF PROTOZOA 



and bodonids deserve mention. These organisms are slightly to 

 extremely plastic; a supportive function for the fibrils is strongly 

 indicated, although there is room for suspicion of contractility. 

 Pellicular fibrils of Trichonjmpha (rostral cap), the tetrahymenids, 

 and Euplotes may also provide mechanical strength. Possibly the 

 fibrillar sheets subtending the buccal cavity membranes in Stentor, 

 the ophryoscolecids and, according to Noirot-Timothee (1960), 

 several other ciliates, do too. 



These lists could be extended by considering inconclusive 

 evidence about many other fibrillar organelles, but in view of the 

 magnitude of uncertainty about even the best-known examples, 

 this speculation has gone far enough. 



The third possible function proposed above was information 

 transfer, surely the most controversial of all — we are descending 

 from attractive probability through extreme uncertainty to total 

 confusion. Presumably any structure with distinct spatial organiza- 

 tion that is capable of transferring electrons — as protein fibers 

 are, according to Szent-Gyorgyi (1960) — can transmit informa- 

 tion of a sort from one extremity to the other. Thus we need not 

 think that by assigning hypothetical functions to some fibers we 

 have excluded them as subjects of further hypotheses. Several 

 functions of protozoan bodies seem to demand the intervention 

 of some means of information transfer more direct and precise 

 than general cytoplasmic states or unchanneled diffusion of 

 messenger substances. These include the careful programming 

 of morphogenetic events, the coordinated contraction and relaxa- 

 tion of bodies or body parts, and, most conspicuously, ciliary and 

 flagellar cooperation. 



According to several recent accounts, membrane transmission 

 of an excited state, in quite the conventional fashion, could 

 account for changes of activity in the somatic ciliature of Opalina 

 and several ciliates (Okajima, 1953, 1954a, 1954b; Naitoh, 1958 ; 

 Parducz, 1958b; Jahn, 1960). According to other recent reports 

 (e.g., the careful experiments of Sleigh, 1956, 1957) as well as a 

 mass of older literature — little of it experimentally viable — the 

 activity of specialized ciliature such as that in the adoral membra- 

 nelles of Stentor requires a more subtle explanation. It is certain 

 that no fibrillar system described for Opalina, Paramecium, and the 

 tetrahymenids could, by its distribution, be held responsible for 



