Chromatuphorc's and Color Change 



683 



In conjunction v\ith both of the preceding groups of methods, technics 

 have often invoKed photomicrography'-' or the rapid (often heatj lixation 

 of the animal for more leisurely analysis later, using temporarx or perman 

 ent skin preparations.-''- "'"" 



Morphological Color Changes. Morjihological color changes inxoKe the 

 accumulatit)n or chemical production or the destruction of pigment within 

 the chromatophores. In the normal adapti\e color changes of animals, jihy 

 siological and morphological color changes proceed simultaneouslv . The 

 morphological changes ma\' result in both an increase in the amount ol 

 pigment within each pigment cell and an increase in the number ol lunc 

 tional chromatophores per unit area of skin.--' '-" Quantitative studies ol 

 morphological color changes have corre>pondingly invoKed two tspes ol 

 technics: (1) the determination of changes in the number of lunctional 

 chromatophores per unit area of surface, and (2) the determination ol 

 changes in the total pigment content of the animals by chemical extrac- 



Fig. 259. A, Graph showing rate of loss of red pigment frcjm the bodies oi: PaJiicnuiiictes 

 kept on a white background. B, Graph showing increase in quantity of red pigment in 

 the bodies of animals kept on a black background. From Brown." 



tion and colorimetric determinations of pigment c]uantity in the extracts''"' 

 (Fig. 259). This whole subject has been abl\ rexiewed tor xcrtchrates 

 by Sumner,'''" and in general the situation among in\ertebrates seems to jmc 

 sent a quite similar picture. 



There appears to be a close functional relationship between physiological 

 and morphological color changes. A correlation between the two has bed 

 noted by many in\estigators.''"'- '- Maintained conccntrdiion ol a jiigment 

 within a chromatophore seems usualK to be correlated with a reduction in 

 quantitv of that pigment, and, con\ersel\, pigment tlisjxrsion apjiears asso- 

 ciated with the pigment production. 1 he expression ol this relationship has 

 sometimes been referred to as Babak's law.'- It would appear either (1) that 

 pigment formation or destruction resulted Irom the state ol dispersion ol the 



