Hadley, Behavior of the American Lobster. 23 1 



less scattering negative reaction at first resulted. When the amount 

 of hght was increased by supplementing the acetylene with a bril- 

 liant oil burner the response was more definitely negative. 



Case ^— July 21, 9 a.m. Twenty-two eighth-day, early third- 

 stage larvae were taken from one of the hatching bags and put in 

 the glass jar m the dark box. When subjected to subdued day- 

 light through the three by one inch window, sixteen out of twenty- 

 two gave the negative reaction. In orange light the reaction was 

 seventeen negative, five positive; in red light eighteen negative, 

 four positive. Here attention may be called to the fact that these 

 third-stage larvae gave a negative reaction to practically the same 

 intensity of light as determined a positive response for larvae in the 

 late second stage. 



Case 5— August 3, 2 p.m. Twenty eighth-day, early third- 

 stage larvae were taken from the hatching bags and put in the glass 

 jar in the dark box. They were submitted to the colored lights, 

 with results as follows: 



Color. t, 



Positive. Negative. 



Red jj 



°""g^ :::::::::::::::;:::::;::::;::: l \\ 



Crreen ^ 



Blue 3 17 



White I '^ 



Day ^ 14 



o 20 



Conclusions from Experiments 19 and 20: The conclusions 

 which we draw from the two foregoing experiments support fur- 

 ther those formulated for Experiments 16, 17 and 18, on p. 228 

 In Experiment 20, Case i, was observed the definite positive 

 response which was manifested toward the end of the second 

 larval stage when the moulting-period was near. In Case 2 

 where a group of larvae which included individuals of both the 

 second and third stages was used, it was observed that the reaction 

 was either positive or negative; and that those larvs which o-ave 

 the negative reaction most definitely or gave it first were usually 

 the larvae of the early third stage. In Cases 4 and 5, in which only 

 third-stage larvae were employed, it was observed that, in general, 

 the reactions to lights of nearly all intensities were negative As 

 m the case of the first-stage larvae, it was found that the reaction 

 of second-stage larvae, just before the moulting-period, usually 

 changed from negative to positive, and again became negative 

 at the beginning of the third larval state. 



