322 Journal of Comparative Neurology and Psychology. 



death only momentarily and then resumed its efforts to go to the light. 



A repetition of the experiment was followed by essentially the same result. 

 When dipped in water again it showed a faint negative reaction. It would go 

 towards the light when it was placed in front of the body or away from it when 

 it was placed behind. Its general behavior was sluggish and it would perform 

 only scarcely perceptible swaying movements when the light was moved over its 

 body. Soon its negative reaction became more pronounced and it would turn 

 away from the light every time it was placed to one side of the body. The insect 

 was then placed under a bell jar near the light and upon my return after a two 

 hours absence it was markedly positive. When dipped in water it showed a 

 suggestion of a negative reaction, and for some time was apparently indifferent 

 to the light. Repeated dippings failed to make the specimen more negative, 

 and after a time a sluggish positive response began to appear. The light was 

 then moved around it and finally the creature became very violent in the eager- 

 ness of its response and flew towards the light several times. When it was dip- 

 ped in water it became sluggish. When placed at right angles to the rays it 

 turned away from the light and started to do so a second time, but turned to- 

 wards the light and went up to it. The same experiment was repeated three 

 times in succession, and each time the insect turned at first away from the light 

 and then towards it before having proceeded more than a few inches. After 

 thirty minutes of positive reactions it was dipped in the water again. It went 

 slowly towards the light but passed by it, and in several subsequent trials went 

 away from the light ; soon, however, it became weakly positive and in a short 

 time its positive response was strong. After three hours of exposure to strong 

 light it was still positive. When dipped into the water it showed at first a faint 

 negative response but soon turned and went up to the light. Subsequent dippings 

 failed to evoke a negative response. 



It is not the effect of water in itself that changes the 

 response, but the experience of being dipped in water. If the 

 Ranatras are allowed to remain in the water they soon show a 

 positive reaction. If then they are lifted out and put on the 

 table they almost at once become negative if they are not 

 thrown first into the death feint. Curiously enough, dipping 

 into water is more effective in changing the sense of the re- 

 sponse than handling or stroking the specimens in the air. 

 Specimens which have been handled so much that they no 

 longer respond to that treatment either by feigning death or by 

 showing a negative response to light may usually be rendered 

 negative after dipping into water. 



As handling positively phototactic specimens usually causes 

 their reaction to become negative, unless the experiment is 

 repeated too often, it is probable that the change produced by 

 dipping them in water is due to the influence of contact stimu- 



