CHAPTER VIII 



THE PITUITARY BODY IN RELATION TO THE 



REGULATION OF THE DISTRIBUTION OF 



PIGMENT IN CHROMATOPHORES 



CELLS containing granules of pigment of various 

 colors may be found in the skin and other tissues 

 of cold-blooded animals. These cells often are of 

 great importance in the adaptation of color to background 

 or in effecting color changes for other purposes — e.g., that 

 associated with the breeding season. The change of color is 

 effected by the movement of the granules of pigment, 

 chromatosomes, in cells which are called chromatophores. 

 These cells commonly are named in accordance with the 

 color of the pigment they contain. Melanophores are so 

 named because they contain melanin-granules for which the 

 term melanosomes will be used. Likewise erythrosomes refer 

 to the granules of red pigment in erythrophores, etc. 



The pituitary body is of importance in this aspect of bi- 

 ology because extracts of the pars intermedia (or of the pars 

 glandularis) may bring about a striking dispersion of chroma- 

 tosomes, especially melanosomes or erythrosomes. The re- 

 moval of most of the pituitary may be followed by the oppo- 

 site effect, e.g., a marked concentration of the melanosomes 

 may follow hypophysectomy in the frog. In addition. Hog- 

 ben and his collaborators have inferred that a hormone of the 

 pars tuberalis is important in certain amphibia in bringing 

 about adaptation to light backgrounds. 



The degree to which the position of pigment-granules in 

 chromatophores is regulated by the pituitary body varies 

 greatly in different classes of animals, such as fishes, am- 

 phibia, and reptiles. The importance of the gland generally 



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