242 



REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



These results seem to show that the first larval stage of Homarus 

 is negatively photopathic on a black background, with weak, medium 

 and bright light; but that, while on white backgrounds he is, under 

 medium intensity, negatively photopathic, if the intensity of light is 

 increased he becomes positively photophatic. Similar results were 

 obtained with second and third stage larvae under similar conditions 

 of light and background. The reactions manifested under the con- 

 ditions of white background and light of low intensity were, as a rule, 

 not as definite as the others. 



Experiment IV. 



Conditions: White Background; Red Monochromatic Light; 

 20 First Stage Larvce. 



Teat. Light end. Mid-area, Dark end. Cover. 



1 2 1 17 



2 2 3 15 



3 3 4 13 Reversed. 



4 6 2 12 



Experiment V. 



Conditions: White Background; Blue Monochromatic Light; 

 20 First Stage Larvce. 



These two experiments indicate that in the case of a white back- 

 ground and red monochromatic light, the first stage lobsters are nega- 

 tively photophathic, while in the case of a white background and a 

 blue monochromatic light the same lobsters are positively photo- 

 pathic. This was naturally somewhat unexpected, but in all the 

 experiments involving similar conditions of light and background the 

 second and third stage lobsters respond in a similar manner. In 



