182 WILLIAM BRODBECK HERMS 



caused individuals to move away from the light to the opposite 

 side and underneath the fish. 



2 :40. By this time all the larvae had crawled away and were 

 beneath the flesh, and individuals did not return to the light side 

 which would have been done in this time were such a reaction to 

 take place. Now the red and orange bands were cast on the flesh. 

 In five minutes the larvae began moving toward the light, taking 

 a diagonal course away from the flesh into and through the yellow 

 band. 



3:00. A mass of at least 150 larvae had collected in the yellow 

 band with many coming from the flesh and some returning toward 

 it. The collected larvae were 3.5 to 4 cm. distance from the flesh 

 and many of them had crawled 2 to 3 cm. up the face of the box. 

 In going toward the light the larvae followed a diagonal path 

 from the flesh which took them out of the red and orange bands 

 into the yellow, across which they travelled to the green band. 

 When the green band was encountered they changed their course 

 by taking the path on the border of the j^ellow, following this 

 course to the edge of the box nearest the source of light. (The 

 change in direction indicated could not be due to unequal distri- 

 bution of moist surface, since the entire bottom was weir' smeared" 

 with fluids from the flesh.) This behavior massed the larvae in the 

 yellow band nearest the green, into the edge of which this aggre- 

 gation naturally grew, but the collecting here was compensated 

 for by a movement away from the green into the more intense 

 yellow portions, never through the green into the blue end. The 

 larvae that left the mass by crawling along the inner edge of the 

 box, probably a thigmotactic response, encountered the orange, 

 which was followed back to the fl(sh. Some individuals also 

 took this latter route toward the flesh, and some returned by the 

 route usually taken to the flesh. Not more than 60 to 75 larvae 

 were separated from the general mass at any one time. 



3 :45. The violet end of the spectrum was thrown on the mass for 

 a few minutes, causing a general movement away from the source 

 of light. The larvae were then left in semi-darkness for an hour 

 during which time they remained in the same general position 

 as during the earlier part of the experiment. 



