422 JOHN B. WATSON 



nation for a small part of the process of adaptation, but Hess 

 maintains that the process as a whole is physiological. 



The forward migration of the pigment in light exposure alters 

 the general effect of the light. The advanced pigment absorbs 

 relatively more of the short wave-lengths than of the long. 

 In order to obtain a relation of equality (for the fish) between 

 given red and blue lights one must use a blue 4-8 times as intense 

 for the eye with pigment advanced as that used for the eye with 

 the pigment retracted. The pigment absorbs little of the green 

 rays. This is shown by the fact that the fish which collect in 

 the brightest part of the container seek the yellow-green both 

 when the pigment is in the forward position and in the retracted. 



The physiological changes in light (monochromatic) intensity 

 incident upon the migration of the pigment might easily be con- 

 fused with the Purkinje phenomenon, as was done by Bauer. 

 Hess still emphatically denies that there is any such phenomenon 

 present, and reaffirms his old conclusion that the fish are color 

 blind. It is interesting to note that he everywhere emphasizes 

 the low stimulating value of red. 



Bauer (1) in an extended reply to Hess (see this journal. 

 Vol. 1, p. 432, for review of Hess' criticism) reasserts his con- 

 clusions that the fish in the light-adapted state are strongly 

 stimulated and even terrified by red (rotscheu) and that they 

 behave as though the Purkinje phenomenon were present. In 

 the last paper just reviewed Hess (p. 419) says that Bauer's 

 results are clue to error, and that on repeating the experiments 

 upon Atherina he finds that the animals do not avoid the red 

 either in the light-adapted state nor in the dark-adapted state. If 

 this is true, and Hess' work is everywhere consistent, the bottom 

 of the quarrel drops out. Bauer's contention that the fish when 

 light-adapted are normal in color vision and when dark-adapted 

 are color-blind is absurd upon its face. His only real support 

 of so strange a position lies in the asserted fact that the light 

 adapted fish are "red-shy"— i.e., that in addition to its bright- 

 ness value red has a peculiar shock effect. Furthermore, from 

 Hess' work on pigment migration we might very well expect a 

 difference between the light-adapted and the dark-adapted fish 

 in their responses to red and blue-green. This it would seem 

 does away effectually with Bauer's claim for a Purkinje effect. 

 The point is more important than would appear at first sight. 



