Holmes, The Reactions of Ranatra to Light. 329 



//. The Effect of Destroying or Covering One Eye. If 

 one eye of Ranatra is blackened over or destroyed the insect in 

 most cases no longer walks in a straight line but performs more 

 or less decided circus movements towards the normal side. 

 Under the stimulus of light the insect assumes a peculiar atti- 

 tude ; the body leans over towards the normal side and the head 

 is tilted over in the same direction. When a light is held oppo- 

 site the normal eye the insect leans over towards it, and holds 

 the legs nearest the light in a flexed condition while those on 

 the other side of the body are extended. When the light is 

 passed over the body transversely swaying movements are per- 

 formed as long as the light is opposite the normal eye, but 

 when it is passed to the other side of the body the insect sways 

 back only to the middle position or slightly farther. The lon- 

 gitudinal swaying movements of the body and vertical move- 

 ments of the head are performed when light is moved forward 

 and backward above the insect. These movements become 

 less decided, however, as the light is held over towards the 

 blind side. 



Fig. J. Head of Ranatra fusca showing the almost stalked condition of the 

 eyes. 



If a light is held directly in front of a Ranatra with one eye 

 blackened over the insect frequently does not travel straight 

 towards it, but veers over towards the normal side until it 

 comes to go in a quite different direction from that in which it 



