Chromatophores and Color Change 717 



ones involving adaptation of the animal to its background through a func- 

 tional relationship between the eyes and the chromatophores, although total 

 amount of illumination, temperature, humidity, tactile stimuli, endogenous 

 rhythms, and other factors may also influence the process. 



The reflex pathways, initiated at the eyes, which are responsible for 

 the control of the color changes in all crustaceans, insects, amphibians, and 

 many fishes and reptiles, involve hormones. Both blood-borne hormones and 

 direct innervation operate importantly in most other species, with the pos- 

 sible exception of the chameleon among the reptiles and such fishes as 

 Fundulus among the teleosts, and possibly also in leeches where purely 

 nervous reflexes possess dominant or exclusive control. Responses of the 

 chromatophore system to Hght continue in most animals in the absence of 

 the eyes, either through the responses of the chromatophores acting as in- 

 dependent effectors or reflexly through other light receptors, e.g., the pineal 

 complex. These latter responses are responses only to intensity of illumination 

 and bear no relation to color of background. These latter reactions typicallv 

 operate to render the animal darker in higher illumination and lighter in 

 lower. 



Several functions have been ascribed to the chromatophore system, among 

 them being: (1) protective and aggressive coloration; (2) thermoregulation; 

 (B) protection of the body tissues from intense illumination; and (4) mating 

 color displavs. 



REFERENCES 



1. Abramowitz, a. a-., Proc. ISat. Acad. Set. 21:132-137 (1935). Morphological 

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2. Abramowitz, a. a., Proc. Nat. Acad. Sci. 21:677-681 (1935). Adaptation to 

 colored backgrounds, Crustacea. 



3. Abramowitz, A. A., Biol. Bull. 71:259-281 (1936). Hypophysis and color change 

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4. AbramovvITz, a. a., Proc. Nat. Acad. Sci. 22:233-238 (1936)'. Dual innervation 

 ot teleost melanophores. 



5. Abramowitz, A. A., Am. Nat. 70:372-378 (1936). Independence of action of 

 melanophores and xanthophores, Fundulus. 



6. Abramowitz, A. A., Biol. BjiU. 73:134-142 (1937). Role of hypophysis in 

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7. Abramowitz, A. A., and Abramowitz, R. K., Biol. Bull. 74:278-296 (1938). 

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8. AscHERsoN, Arch. Anat. Physiol, wiss. Med. 7:15-23 (1840). Color change, frog. 



9. Atwell, W. J., and Holley, E., /. Exper. Zool. 73:23-42 (1936). Pituitary in 

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10. Atzler, M., Ztichr. vergl. Physiol. 13:505-533 (1930). Relation of eyes to Dixip- 

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11. Babak, V.., Arch. ges. Physiol. 131:78-118 (1910). Color change in young 

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12. Babak, E., Arch. ges. Physiol. 149:462 470(1913). Relationship of morphologi- 

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13. Ballowitz, E., 7jschr. wiss. 7.ool. 56:67.3-706 (1893). Innervation of melano- 

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14. Bauer, V., Ztschr. allg. Physiol. 16:191-212 (1914). Melanophores in heat 

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15. Bowman, T. E., Am. Nat. 76:332336 (1942). Morphological color-change, 

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16. Bozler, E., Ztschr. vergl. Physiol. 7:379-406 (1928). Cephalopod chromato- 

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