222 journal of Comparative Neurology and Psychology. 



about equally on each side. Next they were returned to the dark 

 box and submitted to the weak light from the small window. 

 Here they manifested a definite positive reaction which continued 

 until evening. At 8:30 these fifty larvae were suddenly submitted 

 to the intense rays of an acetylene light. The result was a uni- 

 versal negative reaction. Within two or three minutes, however, 

 a few larvae began to return toward the light, and within four 

 minutes all had become positive in their reaction. 



Case 2 — A group of fourth-day first-stage larvae in the glass jar 

 was subjected to light of low intensity and found to manifest a 

 positive reaction; when subjected to a much stronger light the 

 same larvae were still universally positive. This reaction, once 

 established, endured through the period of gradually diminishing 

 intensity of light accompanying the coming of night. The next 

 morning these (now fifth-day) larvae were found to be negative 

 in reaction. It was feared, however, that the manner of reaction 

 might have been changed because of the long period of confine- 

 ment which they had undergone. For this reason a fresh lot of 

 twenty-five larvae from the same group (fifth-day, of the first and 

 second stages), was secured. It was observed at this time that 

 about a third of the number of those in the hatching bag had 

 moulted into the second stage, and that the others were very near 

 the moulting-period. When these larvae were put in the glass 

 jar, placed in the dark box and submitted to subdued light from 

 the small window, six tests showed fifty-five to be negative, and 

 ninety-five positive. When these same larvae (now thirteen first- 

 stage and twelve second-stage), under the conditions of stimula- 

 tion stated above, were subjected to light of still greater intensity 

 by placing the jar nearer the small w^indow of the dark box the 

 results showed that fifty-nine were negative and forty-one were 

 positive. 



At 3 130 p.m. these same larvae were removed from the dark box 

 and placed (in the glass jar) on the west table, where they were 

 suddenly subjected to the bright afternoon sunlight. Every larva 

 came to the room side of the jar and remained there so long as 

 observed. 



Case J — The larvae mentioned above were liberated and another 

 lot of twenty-five (of the same group, but all in the second stage) 

 was secured at 8 o'clock in the evening. The intense rays of the 

 acetylene light were suddenly directed upon one side of the jar. 



