Hadley, Behavior of the American Lobster. 22/ 



Case 2 — In the evening, when other observations were made 

 upon the same group under the influence of the acetylene Hght, 

 burning dimly, the reaction in the glass jar was positive under all 

 the colored glass plates. When the intensity was increased by sub- 

 stituting a lamp which burned more brightly, the group divided,, 

 half going to the positive and half to the negative side. When the 

 intensity was increased still further (reinforced by a brilliant oil 

 burner and reflector) a greater number gave a negative reaction. 

 As it afterward transpired, the larvae used in these last tests did 

 not moult to the second stage until on or after the fifth day. 



Case J — July 23, i :20 p.m. Fifty fourth-day, first-stage larvae 

 were put in the glass jar and placed in the dark box. In the red 

 light the reaction was definitely positive. The reaction under 

 the different intensities obtained by colored glass plates may be 

 tabulated as follows: 



Color. Positive. Negative. 



Red 50 o 



Orange 47 3 



Green 43 7 



Blue 36 14 



White 23 27 



Case 4. — July 31, 10 a.m. Twenty-eight first-stage and second 

 stage larvae of the fifth day (all nearly ready to moult to the second 

 stage) were put in the glass jar and placed in the dark box. Under 

 lights of diff^erent intensities the results were as follows: 



Light. Positive. Negative. 



Red 28 o 



Orange 22 6 



Green 18 10 



Blue 12 16 



White 14 14 



Daylight o 28 



In this particular case it was observed that under the orange light 

 the negative larvas were of the second stage, while those which 

 retained for the longest time the positive reaction (in the case of 

 the blue and white glasses), were the lobsters which were nearest 

 to the moulting-period. When fresh, clean larvae, which had 

 moulted into the second stage within a very few hours, were 

 selected and submitted to several different intensities of light, they 

 invariably gave the negative reaction. 



