5> C. J. CONNOLLY. 



Hess (1910), a leading investigator in the field of color vision 

 in animals, maintains, however, that fishes see the various parts 

 of the spectrum exactly as a color-blind person does at any in- 

 tensity of light, or as a normal person does at lowered intensity. 

 Bauer (1910 b) says this is true only of dark-adapted fishes. 



Von Frisch (1911, 1912, 1913) carried out many exact experi- 

 ments with Phoxinus and other species and has come to the con- 

 clusion that fishes discriminate colors as well as simulate the back- 

 ground. Hess (1913) maintains, however, that the color of the 

 background has no influence on the color of Phoxinus. 



Freytag (1914) also found no evidence of color simulation in 

 Phoxinus, but subjected the fishes to the stimulus for only twenty- 

 four hours. 



Summer (1911) found that certain flatfishes simulate the back- 

 ground not only in shade and color but also in pattern and his 

 photographs given ample evidence that at least these species do so. 



Mast (1916) in a very detailed study of the flounders Para- 

 HcJithys and Ancylopsetta, proves that these species simulate the 

 background in pattern as well as in shade and color and gives ex- 

 cellent autochromes illustrating the colors assumed. 



Reeves (1919) using the method of food association and un- 

 learned responses, and equating the light intensities, concludes 

 that the sunfish (Eupomotis gibbosus L.) and horned-dace 

 (Semotilus atromaculatus) discriminate light of longer wave- 

 lengths from light of shorter wave-length and from white light, 

 while Ohashi (1921) finds in support of Hess that goldfish and 

 carp are unable so to discriminate, their responses being caused 

 by different light intensities. 



During the winter of 1922-23 experiments on Fundulus hetero- 

 clitus were carried out at the Zoological Laboratory, Harvard 

 University, giving positive results which we shall now describe. 



II. ADAPTIVE CHANGES ix SHADE. 



Parker and Lanchner (1922) have recently made tests to ascer- 

 tain the effect of illumination on the shade of Fundulus. They 

 found that the fishes when placed in a white environment repre- 

 sented by a box lined with white paper and illuminated by an 

 incandescent lamp, were of a light shade ; those placed in a 



