246 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



positive photopathic reaction from any of the thousands of young 

 larvse in the large canvas bags. This was accompHshed by means 

 of an acetylene light so directed against a certain area of the white 

 field of canvas that large numbers would at once group themselves 

 thickly about the illuminated area, manifesting, in the case of the 

 third and fourth stages, such an effort to come into the light area that 

 they would often throw themselves partially out of water, causing 

 thereby numerous surface ripples. Since, however, as has been stat- 

 ed, similar results could be obtained when a black background was 

 employed with the acetylene rays, and since the results were not so 

 definite when the incident rays struck the water perpendicularly as 

 when they were thrown at an angle, it was assumed that these re- 

 actions were not manifestations of true photopathy, but were largely 

 due to the effort on the part of the young lobsters to move in the 

 direction of the incident light rays. This phenomenon was better 

 observable in the fourth stage of Homarus, when the very definite 

 rheotactic proclivity, first clearly observable in this stage, could be 

 entirely broken up by introducing the incident rays either at right 

 angles to or in opposition to the direction of the current. A diagram- 

 atic representation of the effect of combining the opportunities for 

 the manifestation of rheotaxis and phototaxis at the same moment 

 is given in the figures of Plate XXXIX. In every observation made, 

 whatever might be the direction in which the light rays were intro- 

 duced, this effect was the same; the phenomenon of rheotaxis ia 

 the fourth stage lobsters was always lost in that area where the light 

 rays had their full effect. A clearer view of the nature of this re- 

 action may be obtained from the description accompanying the 

 plate mentioned above. 



The slight number of observations on the influence of light on the 

 orientation and progressive movement of young lobsters does not, at 

 the present time, warrant far-reaching deductions regarding the 

 probable behavior of young lobsters under natural conditions or 

 suggest aught that might be of value in methods of artificial pro- 

 pagation of lobsters. The writer, however, hopes to discuss this 



