V 



THE NERVOUS SYSTEM AND 

 CHROMATOPHORES 



Brucke (1852) in his account of the color changes in 

 the African chameleon compared chromatophores to 

 ordinary muscle and declared that color-cells with their 

 pigment concentrated were in a condition comparable 

 to that of active, contracted muscle. This idea that the 

 phase of concentrated pigment is the active phase of a 

 chromatophore has been accepted by the majority of 

 workers (Keller, 1895; von Frisch, 1912^; Spaeth, 1916; 

 Giersberg, 1930; Sand, 1935). Carlton (1903), how- 

 ever, was led to reverse this view for Anolis in that he 

 declared that in this lizard the concentrated state was 

 the state of rest. Babak (1913) went still further and 

 expressed the view that both extremes, that of full con- 

 traction and of full dispersion, were conditions of activ- 

 ity probably in contrast with some intermediate resting 

 phase. 



It is not my intention to discuss this question at 

 length. In fact it would probably be ill advised to do 

 so, for, in my opinion, more work should be done in this 

 general field before a sound conclusion can be reached. 

 Suffice it to say that all the views thus far expressed 

 are based more or less implicitly on a supposed simi- 

 larity between chromatophores and muscle, especially 

 skeletal muscle. Such a comparison, as I have else- 

 where intimated (Parker, 1935^/), appears to be quite 

 erroneous, and I believe that we should do well in 

 reflecting on the physiology of chromatophores not to 

 let it bias our thoughts. 



It is probable that the active states of chromato- 



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