COLOR CHANGES AND ADAPTATION IN FISHES. 



187 



not be seen at all when viewed from such a small angle of elevation as the eyes of these 

 animals have. 



The fishes were supplied with oxygen by means of a continuous stream of sea water 

 from the storage tank. This water flowed out of the dish through a siphon so arranged 

 as to insure in the dish a constant depth of water. This could be varied as desired by 

 simply raising or lowering the dish. (Text fig. i, p. 186.) 



The different sorts of backgrounds used in these experiments and the general results 

 obtained are summarized in tables 11 and iii and in the photographs reproduced on 

 plates xxi-xxxv. 



Table II. — Relation Between the Pattern in the Skin of the Fish and the Form, Size, and 

 Arrangement op the Figures in the Background. 



o In this test the background was continuously rotated. 



Table III. — Relation Between the Pattern in the Skin of Flounders and the Size and 

 Total Relative Area op Black Circular Figures on a White Background. 



By referring to table ii and plates xx-xxxv, it will be seen at once that there is. 

 on artificial backgrounds as on natural bottoms, a tendency in the skin of the fish to 

 assume an appearance somewhat similar to that of the environment. On a white back- 

 ground all of the black areas in the skin disappear; on a black one frequently all of 



