The Living Machine 315 



stances will respond to a human hand. ." 'The dove was kept 

 in a room where several men were at work, and he directed 

 his display behavior toward these men just as if they be- 

 longed to his own species. Each time I put food in his cage 

 he became greatly excited, charging up and down the cage, 

 bowing and cooing to me, and pecking my hand whenever it 

 came within his cage. From that day until the day of his 

 death, Jack continued to react in this social manner to hu- 

 man beings. He would bow-and-coo to me at a distance, or 

 to my face when near the cage ; but he paid greatest atten- 

 tion to the hand — naturally so, because it was the only part 

 with which he daily came into direct contact. He treated 

 the hand much as if it were a living bird. Not only were 

 his own activities directed toward the hand as if it were a 

 bird, but he received treatment by the hand in the same 

 spirit. The hand could stroke him, preen his neck, even pull 

 the feathers sharply. Jack had absolutely no fear, but ran 

 to the hand to be stroked or teased, showing the joy that all 

 doves show in the attentions of their companions.' When 

 this pigeon was almost a year old it was put into a cage with 

 a female pigeon, but although the female aroused the sexual 

 instinct of the formerly isolated male the latter did not mate 

 with her, but mated with the hand of his attendant when the 

 hand was put into the cage, and this continued throughout 

 the season. Thus the memory images acquired by the bird 

 at an impressionable age and period perverted its sexual 

 tropisms. ' ' '^ 



Light response is a common phenomenon among the fresh 

 water crustaceans. During broad daylight the upper levels 

 of a lake may be almost uninhabited by these little animals, 

 while at greater depths they occur in large numbers. As 

 night comes on they return to the upper regions which they 

 have deserted by day. Loeb has shown that the behavior of 

 some of these animals with respect to light can be totally 

 changed by chemical treatment. Thus the fresh water Daph- 

 nia, Gammarus and other Crustacea when in a condition in 

 which they do not respond to light can be made intensely 

 positively heliotropic by adding some acid to the fresh water, 

 especially weak CO,. If carbonated water or beer be added 

 to water containing some of these animals they "will collect 

 in a dense cluster on the window side of the dish." Other 

 chemicals including alcohol give the same results. The light- 

 minded reader may be inclined to draw an analogy between 

 this behavior and the tendency of some individuals to enter 

 into close communion with a lamp post in the "wee sma' 

 hours." The alkaloids caffein and strychnin on the other 



' Quoted from Loeb, locus citatus, pp. 168-9. 



