190 REPORT OF COMMISSIONERS OF INLAXD FISHERIES. 



readily observed by merely watching the lobsters in their confinement 

 cars, but for the sake of certainty the fifth-stage lobsters were sub- 

 mitted to the same form of experiment to which the larvse of the 

 earlier stages were submitted. The type of reaction presented in 

 the earlij fifth stage-period was found to differ in no way from the 

 behavior of the late fifth stage-period; and both were characteristic 

 of the behavior of lobsters in all later stages. To the last subject the 

 writer hopes to give his attention later. Regarding the phototactic 

 reactions of the fifth-stage lobsters, it may be said that they were 

 invariably negative, and differed in no way from the phototactic 

 reaction of the fourth-stage larva?,— save that in the former case 

 the reactions were more definite and more strongly manifested. 



Unlike the photopathic response in the fourth-stage larvse, these 

 reactions in the fifth stage were invariably negative from the begin- 

 ning of the stage to the end of it. The photopathic reaction of the 

 fifth-stage lobsters, moreover, was even more stable than in the 

 fourth stage, and it w^as wdth some difficulty that a group of fifth- 

 stage lobsters could be driven, by virtue of their negative photo- 

 tactic response, from a region of lesser to a region of greater light 

 intensity. It will be recalled that in the early larval stages the 

 reactions to intensity were invariably subservient to the reactions 

 determined by the directive influence of the light rays. 



Phototaxis Leading to Fatal Results. — It was interesting to note that 

 the negative phototactic reactions of lobsters in the fourth and fifth 

 stages might often be of so extreme a nature that injury to the larvse 

 resulted. In other words, it was freciuently observed that, if the 

 box in which the larvse were contained slanted gradually, leaving at 

 one end a region which the salt water did not cover, the lobsters 

 might be so driven, by the influence of the light rays coming from the 

 opposite end of the box, that, as a result of their negative reaction, 

 they would be "stranded" so to speak, on the "shore." Here they 

 would invariably remain, and in this position they would have 

 perished, rather than turn to face the light and travel into deeper 



