198 O. P. Bellinger. 



of being composed of fibrils. However, I am not ready to say that 

 this is the ease. It remains to be seen what a more powerful mag- 

 nification will show. 



The myonemes in specimens partially teased and killed in 2 per 

 cent, osmic acid show a definite fibrillar structure after staining with 

 the Ehrlich-glycerine mixture. (PL IV, Figs. 3 and 4.) PI. IV, 

 Fig. 3, which is a smal] section of a myoneme teased away from the 

 body, indicates that they send branches into the body. Other obser- 

 vations led me to think that is the case. The body cilia are all 

 outgrowths from myonemes. Stentor thus supports the theory that 

 contractile tissue is fibrillar. 



E'pistylis. 



This form was killed and stained by the same methods as given 

 above. The stain quickly picks out the contractile elements. These 

 are the cilia, the ciliary bands around the peristome and the myon- 

 emes which extend from the outer peristomal band to the point of 

 attachment at the stalk. (Fig. 10.) The definiteness with which 

 the stain picks out these structures leaves no doubt as to their iden- 

 tity. The presence of the contractile elements in these positions 

 explain all the movements of the animal. 



ISTo data was obtained as to the finer structure of the cilia or the 

 peristomal bands. In a teased specimen the finer structure of the 

 myonemes was demonstrated. They are distinctly fibrillar, as shown 

 in Fig. 11, probably send fibrillae into the body. Their relation 

 to the outer peristomal band is also shown in the above figure. In 

 epistylis the myonemes end at the junction of the l)ody with the 

 non-contractile stalk. 



Smooth Muscle. 

 The major part of the work on smooth muscle was done by Duncan 

 in this laboratory at the same time I was working with the contrac- 

 tile tissue in other forms. Reference will be made to his paper later. 

 He did not investigate the stalk of vorticella, which is generally rec- 

 ognized as the starting point for investigations on smooth muscle. 

 Although there are two well-established views as to the seat of con- 

 tractility in the stalks of vorticella, I think there is no doubt that 



