266 'Journal of Comparative Neurology and Psychology. 



rotation and the side swing (Cor. i). In other words, the larva 

 performed a side-somersault, and ended with the back directed 

 below and to the side. Whether it turned to the left or to the right 

 depended upon the direction of the rays in either the a or the c 

 series. At the end of this reaction the larva usually became 

 righted agam with the back above and the head away from the 

 light, and continued its progressive orientation in one direction 

 or the other according as the reaction was positive or negative. 



Corollary j — If the rays striking the eyes of the larva had the 

 oblique direction a^ — a^ or c^ — e\ and were in plane C of Fig. 

 12, the resulting reaction was a combination of the backward rota- 



FiG. 12. For description, see Case i, Cor. i. Fig. 13. For description see Case i. Cor. 2. 



tion and the side swing (Cor. i). That is to say, the larva per- 

 formed a backward side-somersault, became oriented as in Cor- 

 ollary I and 2, again turned the back uppermost, with the eyes 

 directed away from the source of light, and continued its progress- 

 ive orientation, in one sense or the other. 



Case 2. Larva lying with back doivmvard; head toward light — In 

 these instances, the larva was oriented head toward the (closed) 

 window, and back downward. The rays were introduced from 

 before, as in Case i. It may be said that this orientation was 

 difficult to obtain. Often it was necessary to wait fifteen minutes 



