Habits, etc., of the "Walking-Stick" (Aplopus iiiaycri). 51 



actively crawling, thus showing' that they had responded to the faint light 

 of approaching da\' and not to a tired condition. Tliey continued to move 

 actively for more than an hour in the dark-room, and were then put into 

 the light, where they readily came to rest again. 



The fact that they begin movement by brighter light in the evening and 

 stop by paler or weaker light in the morning may possibly be associated with 

 a similar habit of some birds, which go to their roosts by brighter light than 

 that by which they leave. 



A number of dark-room experiments were performed during the day to 

 test the manner and time of response to light and darkness. The dark-room 

 was one arranged for photographic work, having a red glass window that 

 might be covered with a black oilcloth, so that no light was admitted. The 

 door of the room opened into the closed side of the laboratory, thus per- 

 mitting only weak diffused light to enter the room at any time. I was 

 enabled to detect the first movement of the insects in the dark, as the gauze 

 wire of the cage gave a perceptible clicking sound when their feet were 

 moved upon it. 



^^'e may first consider the reactions of normal individuals. Since the 

 experiments gave closely similar results, one may be recorded for illustration. 

 Three females and two males were placed in the dark-room at 10'' 25" a. m. 

 After 15 minutes three were actively moving, while after 20 minutes all were 

 in motion. The door was opened and light admitted at 11 a. m. ; they came 

 to rest in a little more than a minute, and remained so in spite of various 

 loud noises until 11'' ii a. m., when the room was again darkened. The 

 animals began again to move and all five were in active motion within 8 

 minutes. Bright daylight was thrown on them after all had been moving 

 for 3 minutes ; two were at rest in less than a minute, and all were quiet 

 in about 2 minutes. When they had been at rest for 5 minutes the room 

 was for the third time darkened, and after 11 minutes all were active. Light 

 w"as then admitted and two ceased to move within 2 minutes, the others 

 stopping after 5 minutes. 



The dark-room was again closed at iih 45" a. m. and left until 12'' 30" 

 p. m., at which time all of the insects were active. On admitting light they 

 became motionless within 2 minutes. The dark-room was closed for the 

 fifth time at 12'' 55 p. m., after the five " walking-sticks "' had been quiet 

 for more than 20 minutes ; 10 minutes after they had been in the dark two 

 were moving, and all were in motion after 15 minutes or at i"* 10 p. m. 

 Light was admitted at i*" 11" p. m., and all came to rest w-ithin 30 seconds, 

 a very quick response. They were then exposed to light for 10 minutes, 

 then again put into the dark-room. The first one did not begin to move 

 until 17 minutes had elapsed ; the others were moving after being in the dark 

 20 minutes. The first ones to move had disturbed others by striking against 

 them, so that these probably moved earlier than they would have otherwise. 



