CILIATE FIBRILLAR SYSTEMS 261 



isms. Knowing today the general properties and behavior of the long- 

 chain protein molecules, if such fibrils are proteinaceous, as evidently 

 they are, then fibrillar differentiation is one of the most likely kinds of 

 protoplasmic differentiation that might be expected. 



But by the same token, we would not expect all such proteinaceous 

 fibrils to be alike, either structurally or functionally. Both by virtue of 

 their intrinsic properties and their relations to other organelles, some 

 fibrils of protistan cells, or of metazoan cells, may serve for support, 

 others for contraction, and still others for conduction of impulses to and 

 from motor or other organelles. Or any one fibrillar complex may per- 

 form more than one of these, or of other yet unkown, functions. And 

 this duality or plurality of fibrillar functions may obtain for protistan 

 cells and for tissue cells of multicellular organisms. Certainly we know 

 of no evidences contradicting this possibility. 



The actual function or functions of most fibrils or fibrillar systems 

 are not as yet finally known. There can be no doubt about the contractile 

 properties of the myonemes of Stentor, and some experimental evidences 

 indicate a coordinating (conductive) function for some fibrils in several 

 ciliates and in epithelial tissue. The outer fibrillar systems of Varcimecium 

 and other ciliates may be fibrillar, or only apparently fibrillar, as an 

 integral part and pattern of the pellicle. If of the pellicle, then at least 

 one of its functions would evidently be that of support. 



Much more study and more critical analysis of these fibrillar systems 

 are greatly needed by both improved old and newly devised observational 

 methods, perhaps such as that of the recently developed electron micro- 

 scope. Then complementing these observational and comparative studies 

 will be required indispensably, as the crucial test of all of our hypotheses, 

 exceedingly refined and precise tools and methods of experimentation. 

 Even today there are many devices suitable for this purpose, if properly 

 adapted and fully utilized by the ingenious well-trained hands and eyes 

 of thoroughly informed, exceptionally endowed minds. It is a mistake 

 to suppose that such microtechniques are peculiarly difficult and that such 

 problems are really unapproachable. It is rather that these techniques are 

 different and that their use requires special training. With such training, 

 it may be easier to transect a ciliate or a marine ovum, with much more 

 accuracy, than to perform "free hand" some of the disections on macro- 

 scopic organisms. 



By micromanipulative methods and with the aid of other modern 



