234 ^Journal of Comparative Neurology and Psychology. 



The larvae which were used as stated above, and which presented 

 a positive photopathic reaction in every instance, were next trans- 

 ferred to the glass jar and placed in the dark box. Here, and in 

 tubes, the assumed phototactic reaction was uniformly and defi- 

 nitely negative; and this was true in the case of lights which were 

 both of greater and of lesser intensity than in the tests above men- 

 tioned. 



Case /J- — To confirm the results obtained in Case 3, similar tests 

 were made with another group of ninth-dav, third-stage larvae, 

 fresh from the hatching bag. Notwithstanding the fact that this 

 series of observations was not started until 5 o'clock in the after- 

 noon when the light was fading, the results were similar to those 

 obtained in Case 3. That is to say, the photopathic reaction was 

 definitely positive, but the phototactic reaction, as shown when 

 the larvae were transferred to the glass jar in the dark box, was as 

 definitely negative. 



Experiment 22 — The following experiment and observations 

 concern the tenth-day, third-stage larvae. Most of these lobsters 

 were well along in the third stage, and many were covered with 

 body parasites. 



Case I — July 23, 9 a.m. Thirty tenth-day, third-stage larvae 

 were transferred from one of the hatching bags to the glass jar 

 and placed in the dark box. After having been submitted for 

 one-half hour to light coming through the red glass (three by one 

 inch window), the reaction was uniformly negative. In the case 

 of orange, yellow, green, blue and white light the results were the 

 same. In all of these reactions, however, one fact was noticeable, 

 the body-orientation of these larvae was much less definite than 

 in any previous case of the same or earlier stages. 



Case 2 — July 26, 9 a.m. A mixed lot of thirty third-stage larvae, 

 most of which w^ere ten days old, although some were older and 

 some younger, were transferred from the hatching bag to the glass 

 jar. When submitted to the colored lights in the dark box, the 

 following results were obtained; 



Color. Positive. Negative. 



Red 3 27 



Orange 13 17 



Green 8 22 



Blue 13 17 



White o 20 



