BEHAVIOR OF VERTEBRATES 431 



a long time, they would swim up to it and press themselves 

 against the glass surface. By degrees they accustomed them- 

 selves to the new condition, and swam now here, now there. 

 The reviewer does not know whether Bauer means here to say 

 that the fish became positively phototactic when the paper 

 was introduced, or whether the impulse to press against the 

 bright end was due to what is designated "curiosity" in the 

 higher animals. All through the paper he uses positive and 

 negative phototaxis very loosely. The same phenomenon 

 mentioned above, namely, indifference to photic stimuli, was 

 exhibited by these animals in white light of all intensities ex- 

 cept that of bright sunlight or of a very bright artificial light. 

 When light of high intensity was admitted, the fish behaved 

 as if frightened, and swam quickly to the darkened end. When 

 monochromatic light, either from filters or from the spectrum, 

 was allowed to impinge on the unblackened end of the trough, 

 the behavior of the animals remained unchanged, until the 

 orange region was reached. That is, they were indifferent 

 to all regions up to orange. The moment, however, orange 

 was admitted, a sudden change in behavior occurred. The 

 animals were found to be strongly negative to orange and red. 

 The point where the "Rotscheu'' began was at 620-630 M'/J' (once at 

 610 f^f^). The "red-shyness" was apparent when two colored filters 

 were used, half the undarkened end of the trough admitting 

 red light, the other half blue light. The animals in the blue 

 light turned the head toward the light and swam into it. Those 

 on the red side turned the head from the light and sought to 

 avoid it by making trial movements and swimming to the other 

 end. 



The behavior to red is completely changed by thirty minutes' 

 adaptation to darkness. The fish are no longer "rotscheu," but 

 behave toward all monochromatic rays exactly as they do 

 to weak mixed light. " Die Fische schwimmen dann (bei 

 entsprechenden herabgesetzer Gesamtintensitat) nicht nur auf 

 Blau, Grun und Hellgelb zu, sondern auch auf Dunkelgelb 

 und Rot." One gets the impression from these statements 

 that the red, after the animal is dark-adapted, loses its dis- 

 turbing color-value, and possesses only a white-value. 



C. Hess 1", in a caustic reply to this work of Bauer, points 

 out that he himself has shown that in certain of the forms ex- 



