510 Journal of Comparative Neurology and Psychology. 



given five stimulations dail}^ with light of one color. The stim- 

 uli were given one minute apart. Three different intensities i, 

 2 and 4. were used, one being employed each day. The differ- 

 ent intensities were given in the following order : two, four, one, 

 two, etc., and the trials were continued until records were 

 secured of twenty five reactions to each of the three intensities. 

 The results were then tabulated in two distinct groups. One 

 shows the rise of breathing rate under the influence of each of 

 the three intensities (Table IV), and the other indicates the effect 

 of repetition of the same stimulus (Table V). In case of these 

 tests the first respiration after the stimulus was used in calcu- 

 lating the reaction. 



'Using first respiration, as explained. 



The results expressed in Table IV are of a negative char- 

 acter (see last column). Whereas all four birds reacted more 

 vigorously to intensity i than to intensity 2, three 

 were more sensitive to intensity 4 than 2, and the final 

 average showed the animals to be slightly more sensitive to 

 the lowest intensity than to the highest. Results more 

 satisfactory would probably have been secured from a larger 



