236 'Journal of Comparative Neurology and Psychology. 



when coincident with a homolateral stimulation, may even reverse 

 the index of progressive orientation. 



Case 4. — July 24, 9 a.m. Thirty-five eleventh-day, third-stage 

 larvae were transferred from the hatching bag to the glass jar and 

 placed in the dark box. The reactions to the colored lights were 

 as follows: 



Color. Positive. Negative. 



Red 15 20 



Orange 16 lo 



Green 8 27 



Blue 8 27 



White 7 28 



Next, the jar was placed in full daylight, on the table before 

 the west window. All larvae came to the room side. In this case 

 there were seven larvae which became the special object of obser- 

 vation, since they invariably manifested a positive reaction until 

 they encountered daylight. This group was set aside, and before 

 night four of the seven had moulted into the fourth stage; conse- 

 quently their exceptional behavior was due to the fact that they 

 were in a different physiological condition than the majority of 

 the group used in Case 4. 



Experiment 2^. Case i — ^In this experiment is continued the 

 examination of the reactions of other twelfth-day larva? which 

 were approaching the third moulting-period. Twenty-three larvae 

 were placed in the glass jar and observed under the influence of 

 the c6lored lights in the dark box. The results were as follows: 



Color. Positive. Negative. 



Red 6 17 



Orange 15 8 



Green 6 17 



Blue 4 19 



White -J 20 



Case 2 — At 3:30 p.m. Ten larvae from the above groups were 

 transferred to the glass-bottomed box By which was set up over the 

 light-shaft upon the colored glass plates. The results were as 

 follows: Blue, 19; green, 3; orange, 4; red, 4. During the course 

 of the day, many of these ten larvae moulted to the fourth-stage. 



Case J — July 29, 9 a.m. By this date there were very few 

 third-stage larvae left in any of the groups whose actual age was 

 known. Indeed there are few cases in which the development 

 is so slow that the third-stage larvae endures to the thirteenth or 



