344 DWIGHT E. MINNICH 



progress of the experiments, however, DoUey ('16) has published 

 a contribution to this phase of the subject. His methods as well 

 as his results, on Vanessa, differ widely from those to be de- 

 scribed for the honey-bee. Although in his experiments, as in 

 mine, the illumination employed is defined as non-directive, it 

 was very unlike in the two instances. The results obtained by 

 DoUey are described in terms of circus movements of greater or 

 lesser 'angles of curvature;' those obtained by the writer, in terms 

 of degrees turned per centimeter. The conclusions drawn in the 

 two papers are also widely divergent. 



Tt is a pleasure here to acknowledge my deep indebtedness to 

 Dr. G. H. Parker, at whose suggestion this research was under- 

 taken and with whose helpful criticism it was carried on. T wish 

 also to express my gratitude to Dr. E. L. Mark for the courtesies 

 and privileges of the Zoological Laboratory. 



II. LITERATURE 



As early as 1796, Goeze^ (p. 42) recorded the fact that a hornet 

 in which one eye had been painted over with an opaque varnish 

 always flew toward the uncovered eye. Some years later, Tre- 

 viranus ('32, p. 194) described an experiment in which the lower 

 half of the right cornea of a dragon-fly was carefully cut away 

 from the optic nerve, with the result that the animal moved toward 

 the left side. 



Decidedly the most interesting of the earlier observations are 

 those of Dubois ('86) on a phosphorescent elaterid beetle of the 

 genus Pyrophorus. This insect responds positively to at least 

 certain intensities of light, and according to Dubois (p. 209) it 

 is most affected by the yellow-green rays, which also predominate 

 in the spectrum of its own light. The photogenic organs are three 

 in number, one occupying a median ventral position on the first 

 abdominal segment, the other two being situated on opposite 

 sides of the prothorax near its dorsolateral edges. Whenever 

 the beetle begins to creep spontaneously in the dark, the pro- 

 thoracic organs become luminous. During flight the abdominal 

 organ does likewise. 



' I have not had direct access to this work. The above reference is taken from 

 a footnote m Treviranus (32, p. 193). 



