COLOR VISION 357 



Minkiewicz maintains that these reactions cannot be due 

 to intensity difference, since the light in the yellow and green 

 under the conditions of the experiments was more intense 

 than that in any other color, and the organisms were posi- 

 tive to blue in the presence of yellow, but positive to green 

 in the presence of violet. 



The most interesting of the results obtained by Minkie- 

 wicz refer to the change in reaction to different colors. 

 The spider crabs apparently become positive to the color 

 which is dominant in the environment. Lineus and 

 Pagurus, positive to a given color under certain conditions, 

 become negative to that color under different conditions, 

 or positive to some other color, while they remain con- 

 tinuously positive to white light. These reactions have 

 much in common with those of the honey bee to different 

 colors. They show that the creatures, especially the spider 

 crabs, can distinguish colors. This of course does not 

 demonstrate the power of subjective color sensations. 

 It does however indicate that the different rays cause 

 different changes in the organisms; in other words, that 

 they have specific effects w^hich are in some way related 

 to the wave lengths. There is, however, no evidence bear- 

 ing on the question as to whether or not these effects are 

 analogous to those associated with brightness sensation or 

 with color sensation in man or with neither. 



The results of Minkiewicz must unfortunately be accepted 

 with reserve, since he does not describe his methods in 

 sufficient detail to warrant definite conclusions as to their 

 validity, and they have as yet not been confirmed, although 

 similar experiments have been made on other forms. 



Pearse has recently (1909) repeated the experiments 

 of Minkiewicz at Woods Hole, Mass., using Libinia emar- 

 ginata in place of Maja. He obtained no evidence what- 

 ever of decoration in harmony with the environment. I 

 have observed many of Pearse's experiments and repeated 

 some myself, and feel justified in saying without going 

 into details, that there was no evidence of color selec- 



