Harper, Reactions of Perichceta. 



579 



as a rudimentary reaction. Over against such cases must be placed 

 its typical occurrence in unmistakable form in large numbers of 

 cases and its usual appearance in a good majority. In the case of 

 chemical stimuli there is some difficulty in precise localization when 

 a unilateral effect is sought. A slight swelling at the point of applica- 

 tion is indicative of a distinct local effect. All of the data include 

 considerable numbers of undetermined cases, as it was thought better 

 to include all cases observed even when an accurate determination 

 of the direction of turning was not made. This reduces the apparent 

 negativity of the results, but it was thought better to give the data 

 in this way as an index of the obscurity of the reactions in many 

 instances. On the whole the data may be judged to indicate that 

 the effectiveness of a directive stimulus is diminished when the 

 shock produced by it is excessive. This result appears in tables II 



and III. 



TABLE II. 



Showing Percknt of Negative Tropic Reactions in the Different Types 



(Perichaeta). 



TABLE III. 

 Showing Percent of Negative Tropic Reactions (Lumbricus). 



In table II the results for Perichgeta are given; in table III the 

 same for Lumbricus terrestris. In the latter the responses are 



