REPORT OF COMMISSIONERS OF INLAND FISHERIES. 243 



case, however, a black background is used with lobsters of the 

 third stage, several experiments demonstrate a negative photopathy 

 under the conditions of both red and blue light. 



Experiment VI. 



Conditions: Black Background; 20 Early Fourth Stage 

 Lobsters; Sunlight Bright. 



Test. Light end. Mid area. Dark end. Cover. 



1 13 3 4 



2 15 3 2 Reversed. 



3 12 4 4 



4 15 4 1 



When experiments were tried with the fourth stage, however, a 



different reaction was found to occur. On black backgrounds and 

 with white or blue lights of any intensity, the fourth stage lobsters, 

 unlike the first three stages, were positively photopathic. The 

 degree of light intensity made no change in the results, save in that 

 instances where the light was the least intense the reaction was least 

 marked; and when the light was most intense, as obtained by re- 

 flecting rays of light by means of a mirror into the tube, the definite- 

 ness of reaction was most evident. 



When white backgrounds were used in connection with the fourth 

 stage lobsters, it was found that in every case except with the mono- 

 chromatic red light, a positive photopathic reaction resulted. The 

 latter, which was also contrary to expectations, may be outlined as 

 follows : 



Experiment VII. 



Conditions: White Background; Monochromatic Red Light; 

 20 Early Fourth Stage Lobsters. 



Test. Light end. Mid area. Dark end. Cover. 



1 8 5 6 



2 1 6 13 Reversed. 



3 1 10 9 Reversed. 



4 4 5 11 



