Hadley, Behavior of the American Lobster. 229 



Case 2 — July 23, 5 p.m. The larvae used in this case were of 

 the seventh-day group of the second stage, having been taken from 

 the hatching bag at 9 a.m. At 5 p.m. under red, orange, green, 

 blue and white lights, entering through the three by three inch 

 window, all were definitely negative. They had also shown a 

 negative reaction in several intensities of light in the morning. 

 At 7 p.m. further observations were made on the same group of 

 larvae. The following quotation is from the daily note book. 



"July 23, 7 p.m. One of the best demonstrations of the per- 

 sistency of the negative reaction of these seventh-day larvae was 

 exhibited this evening. Larvae taken from the hatching bags at 

 9 a.m. have reacted negatively at every observation during the 

 day. At 7 p.m. it was observed that this group, which still re- 

 mained in the glass jar near the west window, continued to pre- 

 sent a definite negative reaction. This negative response continued 

 until 7:55 p.m., when the light became too faint to determine either 

 a body or a progressive orientation. Here it is to be observed 

 that the negative reaction on the part of these second-stage larvae 

 was continued through a long series of gradually diminishing inten- 

 sities of light. After all signs of body-orientation or progressive 

 orientation had vanished in the cafse of the group of larvae men- 

 tioned above, the intense light from the acetylene lantern was 

 suddenly thrown open one side of the glass jar. A most definite 

 negative reaction resulted. This response, it will be observed, is 

 different from that recorded in Experiment 14, Case 3, for in the 

 latter case the sudden illumination determined a definite positive 

 reaction." 



Experiment 20. Case I — July 24, 9 a.m. Thirty eight-day, 

 second-stage larvae were taken from one of the large bags and put 

 in the glass jar in the dark box. The time of moulting into the 

 third stage was near at hand, and many of the individuals were 

 already "fuzzy" and sluggish in their movements. Illumination 

 through the three by three inch window, by the colored lights, gave 

 these reactions: 



Color. Positive. Negative. 



Red 30 o 



Orange 27 3 



Green 17 13 



Blue 13 17 



Day 13 17 



