The Ciliiim. 185 



oped further in 1879, the fibers are permanent structures. Cilia 

 are, according to him, composed of fine elements, "Inotagnien," 

 which in their resting condition are fibril like and when contracted 

 are more or less rounded. They are arranged with their long axis 

 parallel to that of the cilium. Parker (1905) has expressed himself 

 as in favor of the fibrillar hypothesis, and thinks it ''the most con- 

 sistent thus far advanced as an explanation of the more usual types 

 of ciliary movement." He does not agree in any way with Putter's 

 objections, and suggests that even in the apparently homogeneous 

 flagella there may be fibrillae. 



Ballowitz (1886, '88 and '90), Jensen (1887) and others conceive 

 tlie fibrillae as running the full length of the cilia. They have gath- 

 ered much evidence which supports this view. 



Effect of Killing Reagents on Cilia. 

 Int7'oduction. 



Although many writers have dealt with the effects of killing re- 

 agents on protoplasm, Berthold (1886), Fischer (1894 and 1899), 

 Biitschli (1892), Hardy (1899), Tellyesniczky (1898), Wasitlewski 

 (1899) and others, none so far as I have known have approached the 

 question from the standpoint of visible structural elements of the 

 living tissue. They have, rather, dealt with structures that appear 

 after the application of the reagent. For that reason there has 

 always been a question as to the reality of such elements. In select- 

 ing the cilium as a structure already present, which is as delicate as 

 the finest structures demonstrated in the cell, it has been the thonght 

 of the writer that reagents which produce no change in it would like- 

 wise leave the elements in the cell undisturbed, and thus the struc- 

 tures found in the cell could be considered normal. 



Methods and Mntericds. 



Paramecium caudatum, Stylonychia pustulata and Actinosphaer- 

 iuni eichhornii were used. Probably all the cilia of Stylonychia are 

 compound; that is, composed of a number of fibrils coiled together 

 spirally (PI. T, Fig. 1.) For this reason the effect of the reagents 

 on its cilia are more easily observed, and it was used entirely for the 



