432 JOHN B. WATSON 



perimented upon by Bauer, the red has very Httle stimulating 

 effect; and hence, as I understand him, he would maintain 

 that Bauer's results are due to the fact that the light-adapted 

 animals react to red as they would to darkness; i. e., they swim 

 about only in those areas which appear light to them. On the 

 other hand, when the fish are dark-adapted the red becomes 

 supra-liminal and they react to it as to the other rays. 



Bauer thinks that he was able to demonstrate the Purkinje 

 phenomenon in three of the forms studied, but from his con- 

 tradictory statements and from the arrangement of the appa- 

 ratus it is extremely questionable whether the reactions were 

 due to the presence of the Purkinje phenomenon. He con- 

 cludes his paper with the rather astonishing statement that 

 monochromatic light possesses both a color value and a bright- 

 ness value for the light-adapted fish, but that the dark-adapted 

 fish behave throughout as Hess maintains; that is, as though 

 they were color-blind. 



Reptiles and Amphibians. C. Hess '^^ in a striking series 

 of carefully conducted experiments, shows quite conclusively 

 that the turtle, although its eyes are totally unsupplied with 

 rods, and hence lacking in visual purple, nevertheless possesses 

 the power to adapt itself to darkness to a very high degree. 

 His method for proving this was a very simple one. The light- 

 adapted animal was carried quickly into a dark-room and placed 

 upon a table covered with dead black cloth, with its back to 

 the apparatus admitting graded white light. This apparatus 

 consisted of an electric light contained in a light-tight metal 

 case. This case was supplied at one end with an iris diaphragm 

 working over a ground glass disk. Immediately upon entrance 

 into the dark-room the turtles were presented with a piece 

 of meat (for control tests a small wad of cotton wool was used). 

 The animals were guided in their responses by optical stimuli, 

 Hess tells us, and would, since they were kept quite hungry, 

 snap at the meat the moment it became visible. If, imme- 

 diately after entering the dark-room, the diaphragm admitted 

 sufficient light, the animals would snap at the food. If the 

 opening were too narrow, the animals refused to strike at the 

 food. The diaphragm was accordingly quickly opened to the 

 point where they would snap. This reading was then taken; 



