36 BUTTERFLIES 



distance and then alight, and I was interested to notice 

 that after alighting it would always turn about until the 

 hind end of its body pointed in the direction of the sun, so 

 that the sun's rays struck its wings and body nearly at 

 right angles. I repeatedly observed this habit of getting 

 into the position in which the most benefit from the sun- 

 shine was received, and it is of interest as showing the ex- 

 treme delicacy of perception toward the warmth of sun- 

 sliine which these creatures possess." 



A httle later, some very elaborate observations were 

 made upon this habit of the Mourning Cloak by Prof. 

 G. H. Parker of Harvard University. Professor Parker 

 noticed that during the warm spells in winter the butter- 

 flies came out of their hiding places and after alighting, al- 

 ways placed themselves with their heads away from the di- 

 rection of the sun and their bodies lying nearly at right 

 angles to the sun's rays. By experiment, he found that 

 they adjusted themselves to this position as soon as they 

 were fully exposed to direct sunshine, even if at the time of 

 alighting they were in a shadow. He found that this 

 movement was a reflex action through the eyes, for when 

 the eyes were blinded no such adjustment took place. He 

 called it negative heliotropism. 



Dr. Longstaff uses the term orientation for this adjust- 

 ment of the butterfly to the sun's rays and he finds it is a 

 very general habit, especially with the Angle- wings, for the 

 butterfly thus to orient itself after alighting, in such a way 

 that the hind end of the body points toward the sun. This 

 occurs not only with those species which keep their wings 

 spread open when they alight but also with those in which 

 the wings are closed together and held in a vertical po- 

 sition on alighting. 



