The Cilium. 197 



(PI. II, Fig. 10.) These observations are in agreement with those 

 of Biitschli on the psendopodia of Actiuophjrs. He says: "The 

 protoplasm of the pseudopodia apj)eared in part composed of distinct 

 longitudinal fibers. Moreover, this fibrillar modification of the proto- 

 plasm could be followed through the coarsely vesicular ectoplasm 

 into the finely meshed endoplasm, and at the same time it could be 

 demonstrated that the fibrous tracts pass in^) the meshwork of the 

 endosarc." 



Whether or not the fibrillae of the pseudopodia and of the body 

 reticulum are contractile was not determined with certainty. How- 

 ever, one set of observations indicates that it is. Throughout the 

 entire series of studies Ehrlich's blood stain in dilute glycerine (one 

 drop of stain to one cc. of 10 per cent, glycerine) was used to stain 

 the tissues. It was found that this stain picked out the contractile 

 stalk of Vorticella, the ciliary bands of Vorticella and Stentor with 

 their cilia, and the fibrillae of smooth and striped muscle. It is 

 admitted that these are the contractile elements in these forms. This 

 same stain picked out the fibrils of the pseudopodia of Actinosphaer- 

 ium and the reticulum of the body, which indicates that we have 

 here, also, contractile tissue. 



Ste7itor. 



The contractile elements of Stentor have been described by a num- 

 ber of writers (Metschnikoff, Johnson and Biitschli). They are 

 easily recognized as the cilia and myonemes in the living animal, but 

 require special methods to demonstrate their nature. 



The cilia are of two kinds, those surrounding the peristome, and 

 the body cilia. The former are complex; that is, composed of a 

 large number of delicate fibrils. PI. IV, Figs. 1 and 2, show the 

 cilia after treatment with osmic acid and strong Flemming. From 

 PI. IV, Fig. 2, and Text Fig. it is seen that they are extended into 

 the body as an apparently solid mass. The relations or meaning of 

 this part of the cilia were not determined. It is much like the solid 

 ends of the fibrous core of the pseudopods of Actinosphaerium. The 

 finer structure of the body cilia could not be demonstrated, but in 

 many cases of partly melted down cilia they showed every indication 



