2/2 "Journal of Comparative Neurology and Psychology. 



swimming position with the axis of the body bent downward several 

 degrees from the normal swimming position (perhaps 45°from the 

 horizontal), the exact amount appearing to be dependent upon the 

 intensity of the light. This new swimming position was usually 

 maintained as long as the conditions of light remained unchanged. 

 It might sometimes be interrupted by backward rotations through 

 360°. These rotations invariably culminated in the assumption 

 of the new swimming position (Fig. 18, B). In case the direction 

 of the rays was both from the side and from above the resultant 

 reaction was a combination of the reaction described above and the 

 direct side swing. 



Fic. 18. For description, see Case 7. 



Fig. 19. For description, see Case 8. 



Case 8. Larva oriented with back above; light enters from beloiv 

 — ^Under these conditions of orientation, the nature of the reaction 

 was similar to that described in Case 6. Usually there resulted 

 a direct backward rotation through a few degrees, which produced 

 a new swimming position, Fig. 19, B\ This was usually constant 

 while the conditions of light remained the same, but it was some- 

 times interrupted by backward rotations through an arc of greater 

 extent, or even by a variable number of complete backward rota- 

 tions through 360°. At the end of these, however, the new swim- 

 ming position B' was invariably assumed. Combinations of the 



