Hadley, Behavior of the American Lobster. 215 



and submitted to light ot medium intensity from the small window. 

 There was no appreciable tendency to undergo either body or 

 progressive orientation. The lobsters were much engaged in 

 eating one another. 



Case 2 — The fourth-stage lobsters mentioned in the preceding 

 paragraph were fed on chopped clam meat and placed in box A 

 w^ith the black interior. Light was admitted through the end 

 window. Records of four tests made at two-minute intervals 

 show that while nine were neutral in reaction, six were positive, 

 and twenty-five were negative. The box was next lined with 

 white paper and the same fourth-stage lobsters w^re submitted 

 to the same external light conditions. The results show twenty- 

 six positive, twelve neutral, and twelve negative individuals. 



Case 3 — August 7, 2:30 p.m. When twenty fifth-stage lob- 

 sters, twenty-five days old, were put in box A and illuminated 

 through the end window, all, without exception, oriented in the 

 dark end of the box. 



Conclusions concerning the permanence of these reactions through 

 the stages — In explanation of the ten experiments recorded above, 

 it should be stated that the writer had at his command large num- 

 bers of larval lobsters of approximately the same age and stage 

 which had been subjected throughout the whole of their early 

 life to the same conditions of environment. Therefore it was pos- 

 sible to make a detailed systematic study, not of a few isolated 

 individuals alone, but of whole groups. The result of this study 

 is expressed in these experiments. 



Whatever else the foregoing facts may demonstrate, the answer 

 to our first question is evident. There is ?io constant form of reac- 

 tion on the part of the larval lobsters to the directive influence of the 

 light rays. For this reason one has no warrant for saying, without 

 reservation, that the larval lobster is either positively or negatively 

 phototactic. If it had been necessary to depend for material upon 

 a few individuals of uncertain age, and to draw conclusions regard- 

 ing the general behavior of all the larvae after observing the behav- 

 ior of these few individuals, the outcome would of course be far 

 less satisfactory than in the present instance. It is to be regretted, 

 perhaps, that no means were at hand to make a critical determi- 

 nation of the exact intensities of light to which the larval lobsters 

 gave their recorded reactions, but it is apparent that such a refine- 

 ment of method would not change the general conclusions reached. 



