226 JENNINGS AND JAMIESON. 



notably by Pearl (1900), in the case of Colpidiuin, and by Putter 

 (1900, p. 273), in Stylonychia. In Colpidiuin, according to the ob- 

 servations of Pearl, it is a group of cilia at the anterior end of the 

 body which, invariably striking toward the oral side when the animal 

 is stimulated by the electric current, cause the body to turn toward 

 the aboral side. In StylonycJna it is the entire group* of peristo- 

 mal cilia that, striking toward the oral side, cause the body to 

 turn toward the aboral side. 1 We can testify from our own ob- 

 servations that these relations seem clear. One naturally con- 

 cludes, therefore, that the sidewise motion is determined by these 

 peristomal or anterior cilia, and that if they were removed the 

 motion would no longer occur. Massart (1901, p. 27), on the 

 basis of Pearl's work, accepts the idea that the sidewise move- 

 ment is caused by different cilia from the backward or forward 

 motion, aiding thus to distinguish between what Massart calls 

 pliobisin (the backward movement in reaction) and clinisin (the 

 lateral movement). 



The work here set forth was undertaken for the purpose of 

 getting further light on this and related matters. If the anterior 

 or oral cilia are removed by operation, will the organism no longer 

 turn toward the aboral side when stimulated ? And is the char- 

 acter of the spiral swimming modified by removal of such cilia ? 

 In general, does the removal of specific groups of cilia (with the 

 accompanying alteration of the body form) have specific effects 

 on the movements of the animal ? 



The behavior of pieces of infusoria has been studied by Ver- 

 worn (1889) and Balbiani (iS88). 2 The results of these investi- 

 gators are of the greatest interest, but do not touch specifically 

 the questions raised above. They found that pieces of ciliates 

 move in general in the same manner as do the entire organisms. 

 The reaction to stimuli by turning toward a certain structurally 

 defined side, and the swerving toward a structurally defined side 

 in the spiral course, in the uninjured animal, had not at that time 

 been observed, so that these matters were, of course, not observed 

 for the pieces. The questions proposed in this paper were there- 

 fore not touched by the experiments of Verworn and Balbiani. 



1 These are aided in the turning, according to Putter, by the " running cilia." 



2 Balbiani' s paper we have been unable to consult, so that we must depend upon 

 the account of it given by Verworn. 



