A CILIUM NOT AN AMCEBOID PROCESS. 



239 



are "amoeboid processes." They are composed of firm 

 formed material which retains its characters after death, and 

 does not become changed like every form of bioplasm. In 

 PI. X, I have given some drawings of cilia from the tongue 

 of the frog and toad, figs, i to 5. 



Although the cilium is invariably in close relation with 

 the bioplasm of the elementary part with which it is con- 

 nected, its consistence is very different. Cilia can be 

 detached with portions of bioplasm adhering to them, 

 fig. 3 ; and the latter may, in some instances, be traced for 

 some distance towards the apex of the cilium apparently 

 occupying its central part, figs. 2, 3, 5. It seems to 

 me, therefore, that at least in such instances we must 

 attribute the movement to a change effected by the living 

 matter in the interior of the cilium. I think that the tension 

 of the fluid in the formed material or tissue of the cilium is 

 increased by the action of the bioplasm in taking up nu- 

 trient matter and effecting change in it. As the material in 

 question is elastic, it becomes stretched and then recoils. 

 In this way a " vibration " results. 



The prolongation of the bioplasm into the cilium may be 

 seen under a magnifying power of about 3,000 in good speci- 

 mens examined in a very thin stratum of fluid, and covered 

 with a very thin glass, which must not be allowed to press 

 strongly upon the specimen. In PI. X, figs. 2, 3, 5, I have 

 given drawings of the appearances I have observed in for- 

 tunate specimens. I have also, by the aid of the staining 

 process, succeeded in demonstrating the fact that the bio- 

 plasm extends to a point higher up the shaft of the cilium 

 than one would have been led to suppose from the examina- 

 tion of the structure in the recent state. In connection 



