ADAPTIVE CHANGES IN COLOR OF FUNDULUS. 75 



cytes and the reflecting layer. The guanophores are frequently 

 found associated with the melanophores. 



8. Adaptive change to a yellow background is brought about 

 by a maximum expansion of xanthophores and a maximum con- 

 traction of the melanophores. 



9. In fishes adapted to a red background, the xanthophores are 

 only partially expanded and the melanophores contracted. The 

 pink color is due chiefly to a dilation of the blood capillaries. 



10. In fishes adapted to a green background, the green tints 

 present in the imnnal light adapted fish, is increased and is espe- 

 cially noticeable above the eyes. The xanthophores and melano- 

 ;.h<ire> arc partially expanded. 



11. In blue adapted fishes the xanthophores are maximally con- 

 trarted and tin- in- -lanophores in the deeper portions of the dermis 

 and upi in the ]!' xiinal parts of the scales, are expanded. 



I'nstscript. Since the preparation of this paper I have had the 



opportunity i repeating the experiments on Fnndnlus at the St. 



Andiw 1' i^ical Station. My results have been the same as 



thnxe obtained in the Harvard Laboratory except that I failed to 



on a re<l background the pink coloration and vaso-dilation de- 



;>el in this paper. Whether this is a seasonal or a local difFer- 



-bes remains to be worked out. 



BIBLIOGRAPHY. 

 Ballowiu, E. 



'93 1 iiigen der Pigmentzellen, ein Beitrag zur Kenntnis, des 



'/\\ :-s dcr Kndverzweigungen der Xcrven mit dem Proto- 



I'l.i- n. Zoitschr. wiss. Zool., Bd. 56, pp. 673-706. 



Bauer, V. 



'ioa I cininterschcidiinRsvermogen der Fische. Arch. ges. 



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Arch. }ii-s. Physio!., Bd. 137, pp. 622-626. 

 Cunningham, J. T., and MacMunn, C. A. 



'93 On r raton of the Skin of Fishes, E^'fcially of Pleuronectidae. 



Pin ns. Roy. Soc., London, Vol. 184, pp. r ( '5 s '-- 



Franz, V. 



'08 Hie Smiktur der Pigmentzelle. Biol. Ccntralbl.. IM. ^8, pp. 536-543. 

 515 54 R . 



Freytag, G. V. 



'14 Lichtsinnuntersuchungen bei Tieren. Arch, verpl. Ophthalmol., Bd. 4, 



I'I>. i ? i i ' i 



