198 C. F. CURTIS RILEY 



orienting themselves so that their heads pointed toward or 

 away from the light. In one series of experiments with red 

 and blue lights, out of a total of 960 responses, 788 were toward 

 the blue light, 167 were toward the red light, and 5 were indif- 

 ferent. Viewing the responses from the percentage basis, 82 

 per cent were in favor of the blue light, while only 17 per cent 

 were in favor of the red light. It will be noticed that the results 

 in the main are similar to those obtained with single mono- 

 chromatic lights. However, it should be stated that the re- 

 sponses were not quite so quick as was the case with single 

 lights. There were movements toward both lights, but those 

 toward the blue far outnumbered those toward the red. 



"It cannot be said that there is much evidence in favor of positive 

 phototropism for the red light." (Laurens, I.e., p. 280.) 



In comparing these experiments of Laurens, with balanced 

 blue and red 'lights, with those of Pearse (I.e.) on Rana palus- 

 tris with single blue and red lights, it is of interest to observe 

 that the results in the two cases very largely agree, in that 

 there is a greater number of positive responses toward the blue 

 light than there is toward the red light. How y ever, it should 

 be noticed that there is a much larger percentage of positive 

 responses with reference to the blue light in the former's experi- 

 ments with balanced blue and red lights, than is found to be 

 the case in Pearse 's experiments with blue and red lights used 

 singly. It should also be noticed that in Pearse 's experiments 

 the results indicate many responses that were indifferent with 

 respect to the red light. 



VIII. RESPONSE TO CONTACT 



Some observations were made on young specimens of Bnfo 

 americaniis with reference to their responses to contact stimuli. 

 While no systematic experiments were undertaken in order to 

 study the effect of contact on the behavior of the animals, yet 

 certain incidental observations were recorded. Some data were 

 obtained regarding the influence of contact stimuli on the 

 response to light. Record was made of observations on a form 

 of a contact response resembling the death-feint among Arthro- 

 pods. Some description also was given of the work of other 

 writers with regard to the contact responses of toads and frogs. 



During the experiments with light there were usually a num- 



