Hadley, Behavior of the American Lobster. 249 



vious experiments. In the second instance the blue glass was 

 removed, and the space where it had lain was left clear, thus per- 

 mitting the reflected daylight to enter this area of the bottom of 

 the box. The results of both tests show a negative reaction which 

 was more definite in the second instance. 



2 12 15 30 



Case 2. Phototactic reaction — Further demonstration of the 

 definitely negative phototactic response of fifth-stage lobsters was 

 given by the experiments on contact-irritability (Exp. 29, p. 256). 

 Here is clearly shown the extreme manifestation of this negative 

 phototactic response, which frequently would have culminated in 

 fatal results by driving the lobsters from deep to shallow water 

 and leaving them stranded where they would certainly have died 

 had they not been returned to the water at the end of the experi- 

 ments. Here, as has been found in the case of many animals, the 

 total behavior is completely dominated by the light influence. It 

 may be said further that in the case of the fifth-stage lobsters light 

 of diff'erent intensities does not cause a change of reaction from 

 positive to negative, or from negative to positive, as was the case 

 in the earlier stages; nor do we ever find the individuals "heading" 

 into the light, as may be the case in the fourth-stage larvae. For 

 the fifth-stage lobsters any intensity of light which influences their 

 behavior in any degree, determines, under experimental condi- 

 tions, both a negative body-orientation and a negative progressive 

 orientation. 



In the foregoing pages it has been shown that larvae which were 

 positively photopathic could be made to pass from regions of 

 greater to regions of lesser light intensity by submitting them to 



