VANESSA ANTIOPA LINN. 467 



III. SUMMARY. 



1. Vanessa antiopa, in bright sunlight, comes to rest with the head away from 

 the source of light, that is, it is negatively phototropic, when the surface on which 

 it settles is not perpendicular or very nearly perpendicular to the direction of the 

 sun's rays. When, however, this surface is perpendicular to the sun's rays the insect 

 settles without reference to the direction of the rays. 



2. This negative phototropism is seen only in intense sunlight and after the butter- 

 fly has been on the wing, i.e., after a certain state of metabolism has been established. 



3. V. antiopa creeps and flies toward a source of light, that is, it is positively 

 phototropic in its locomotor responses. 



4. Its positive phototropism occurs with lights varying in intensity from 2 candle- 

 power at 2 metres distance (0.5 candle-metre), to 250 candle-power at 2 metres dis- 

 tance (62.5 candle-metres). Positive phototropism also occurs in intense sunlight, 

 and is not dependent upon any particular phase of metabolism. 



5. Both negative and positive phototropism in this species are independent of 

 the "heat-rays" of sunlight. 



6. The position assumed in negative phototropism exposes the color patterns 

 of the wings to fullest illumination, and probably has to do with bringing the sexes 

 together during the breeding season. 



7. No light reactions are obtained from the butterfly when shadows are thrown 

 upon any part of the body except the head. 



8. When one eye is painted black the butterfly creeps or flies in circles with the 

 unaffected eye always toward the centre. 



9. When both eyes are painted black all phototropic responses cease and the 

 insect flies upward. Butterflies with normal eyes liberated in a perfectly dark room 

 come to rest near the ceiling. This upward flight in both cases is due to negative 

 geotropism, not to phototropic activity. 



10. V- antiopa does not discriminate between lights of greater or less intensity 

 provided they are all of at least moderate intensity and of approximately equal size. 



11. V. antiopa does discriminate between light derived from a large luminous 

 area and that from a small one, even when the light from these two sources is of equal 

 intensity as it falls on the animal. These butterflies usually fly toward the larger 

 areas of light. 



12. This species remains in flight near the ground because it reacts positively 

 to large patches of bright sunlight rather than to small ones, even though the latter, 

 as in the case of the sun, may be much more intense. 



