54 Papers from the Marine Biological Laboratory at Tortugas. 



brought to rest by the uUra-violet rays of sunlight, since they do not move 

 in the absence of such rays. They probably respond, therefore, to the visible 

 rays of the spectrum. 



Ten Apia pi were subjected to light transmitted through blue glass. 

 (Spectroscopic analysis showed this glass to be impure, transmitting blue, 

 green, and a little red and yellow.) The insects gave no definite response 

 in this light, although during one experiment they became more active than 

 usual, moving as if they were in the dark. Such a response was, however, 

 not at all constant and I am inclined to think that the individuals of this 

 experiment had become unduly excited from some other cause. 



The influence of red light, containing possibly a little orange, was tried on 

 ten Aplopi. This also failed to give any definite reaction. It seems likely, 

 then, that these insects respond to sunlight as a complex light and not to a 

 limited number of its rays — at any rate not to the few tested above. 



EXPERIMENTS WITH SOUND. 



Aplopus seems indifferent to loud noises ; a loud voice or a strong rap 

 upon a board is apparently unheard. A 32-caliber pistol was fired three 

 times within 18 inches of three active individuals, one male and two females, 

 yet they gave no indication of having heard the pistol. Before the pistol 

 was fired the second time the " walking-sticks " were made to assume 

 awkward positions ; still they remained motionless after the noise. 



MOVEMENT EXPERIMENTS. 



Aplopiis may be made to assume almost any position, it matters not how 

 apparently awkward, and it will often retain such a position for a long 

 period of time. Such a response may be very useful in causing this animal 

 to be passed unnoticed. If it be shaken or struck while resting on a limb 

 it will not at first scamper off as most insects would, but remains perfectly 

 still in almost any position it may chance to occupy after the shock. When 

 such a disturbance is repeated for several times, Aplopus may become ex- 

 cited and either drop or attempt to run away. One of either pair of legs 

 may be lifted from its foothold and be straightened or twisted backward 

 or forward and left with the foot free and unsupported. The leg may re- 

 main motionless in such a position for long periods of time. Two or even 

 three legs can be raised in such a fashion, and Aplopus will stand motionless 

 an its remaining foothold. Not more than three of its feet can be raised at 

 any one time, since it is unable to support its long body upon only two legs. 

 The antennse may be directed in any direction the observer may wish and 

 the insect will permit them to remain in such a position. One may actually 

 lift an unexcited Aplopus by its long mesothorax and slowly place it back 

 down upon a flat surface, where it will remain for 10 minutes or more with 

 its legs pointing upward. A second individual may be placed in a similar 

 manner over the first, and both will remain motionless for many minutes. 

 As mentioned above, they show a death- feigning reaction. 



