OBSERVATIONS ON THE BEHAVIOR OF BUTTERFLIES 253 



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deviation, sometimes as much as 45 degrees. In course of these 

 observations it was found that the position of the support upon 

 which the specimen came to rest often had a modifying effect 

 as to its final position. That is, if the specimen alighted upon 

 a twig which was slightly out of the line of the rays of sunlight 

 it conformed to the axis of support instead of that of the rays. 

 In one case the specimen alighted upon a dry leaf stem with 

 the head upward, and about 30 degrees from the parallel of 

 the sun's rays. This effect of the influence of the supporting 

 basis was frequently observed in later cases and I think affords 

 an important factor to be taken into account in such cases. 

 Evidently here was a stimulus which served to modify in a 

 very appreciable degree the character of the behavior., On this 

 specimen a number of experiments were made by means of 

 shadows cast upon the body. In some cases these were pro- 

 duced by means of the hand, sometimes by using one's hat, 

 and in some cases by a cane which might be made to cast a 

 definite and localized shadow. Under total shadow the speci- 

 men usually showed reaction in from 5-10 seconds, and within 

 15 seconds would fly into the light (occasionally the movement 

 would be by crawling). Under partial shadows, i.e., a part 

 of the body in shadow, the reaction was less prompt, from 

 15-20 seconds. As in the total shadows, the reaction might 

 involve flight, or a mere creeping forward or sidewise, as the 

 case required. The response was in general more prompt with 

 the shadow on the anterior of the body and head and slowest 

 when the posterior part was under shadow, which would seem 

 to imply the relation of sight in the reaction, though not wholly. 

 On May 27th a series of observations were made under very 

 favorable conditions, the specimens being easily approachable 

 and seldom taking fright or leaving the place. The records of 

 the day included fifty observations, and of these hardly more 

 than half of the photic reactions came within the 10 degrees 

 arbitrarily set as a sort of limit for precise orientation. Varia- 

 tions from 10-30 degrees were very common and in a few 

 cases the variation was definitely 90 degrees from the line of 

 the rays. Experiments with shadows showed some interesting 

 features not noted before. In a few cases total shadow 

 produced no reaction at all ; but in most cases there was response 

 within about the limits already noted. In some cases a specimen 



