412 University of California Publications in Zoology f VoL - 19 



During the winter of 1916-17 when Dr. Tocom had found and was 

 studying the fibrillar system in Euplotes patella, it seemed to me that 

 the experimental method of microdissection might be successfully 

 employed to aid in determining the actual function of this system 

 and that Tocom 's excellent morphological studies might be supple- 

 mented by experimental evidence. 



The value and necessity of experimentation was duly recognized by 

 Dr. Yocom, who has already added several experiments of another 

 sort to this essential phase of the problem. "In studying Euplotes 

 patella" (Yocom, 1918, p. 363) "that have been treated with very 

 weak solutions of certain chemicals, such as neutral red, methylene 

 blue and especially nicotine, it has been noticed that the anal cirri and 

 cytostomal membranelles are the last to cease moving. The other 

 cirri become quiet but the membranelles and anal cirri have been 

 seen to move even after the cytoplasm has begun to break up. Such 

 phenomena favor very strongly the idea that the motorium serves as 

 a coordinating center between the anal cirri and the cytostomal mem- 

 branelles. However, other observations on living animals give even 

 stronger evidence in favor of the neural function. It has also been 

 noted in specimens subjected to a very weak solution of nicotine that 

 the frontal, ventral and marginal cirri continue moving even after the 

 animal has ceased to swim about. The membranelles also move but 

 more slowly than in normal animals. Occasionally one or more of the 

 anal cirri may be seen to make a feeble movement not sufficiently 

 strong to cause the animal to move. However, as the animal revives 

 from the effects of the narcotic and begins to swim about by vigorous 

 kicks of the anal cirri, a decided increase in the rate of movement of 

 the membranelles may be noticed." 



Acknowledgments 



This experimental investigation has been made under the very 

 helpful direction of Professor Charles A. Kofoid, whose kindly and 

 stimulating criticisms have contributed much to any merits the results 

 may possess. 



My thanks are also due to Professor S. S. Maxwell for several 

 valuable suggestions on methods and useful literature. 



