410 STELLA B. VINCENT 



because color vision should be denied an animal as the result 

 of a single investigation, no matter how carefully it may be 

 conducted, but because the results of our experiments certainly 

 make the term ' color blindness ' a less presumptuous one than 

 ' color vision ' when applied to these animals." Colored papers 

 which were tested by two observers by the flicker method were 

 the stimuli. Nine animals in all had 100,000 trials — one cat 

 alone had 1500 trials. Colors were first presented in easily dis- 

 criminable pairs until the selection of the food color was rapid 

 and accurate and then the distance between these colors was 

 varied until confusion colors were found. When one cat con- 

 fused certain colors the same colors were immediately given to 

 another cat, called the follower, to confirm the results. Thirty 

 consecutive choices with twenty-four right in a series was called 

 a discrimination and six hundred failures counted as com- 

 plete confusion. When such confusion colors were finally 

 found they were then paired with grays of the same flicker equiva- 

 lent. The authors say in conclusion: — " It seems probable that 

 cats cannot distinguish any one color from all the shades of gray 

 under light adaptation. It seems probable that cats may be 

 totally color blind by daylight." They also found that both 

 red and blue had a low stimulating power and think that pos- 

 sibly cats have a shortened (gray) spectrum. Yet blue was not 

 confused with black. The paper represents an enormous amount 

 of work. The tables are all given. 



Birds. — A preliminary report of the color vision of the Ring 

 Dove is given by Yerkes (40). The birds were first tested for 

 their reaction to achromatic stimuli. After two doves had been 

 trained to discriminate a bright from a dark area of the same 

 size they were tested for preference for spectral red 626 to 640 

 or spectral green 498 to 510. A modification of the Yerkes- 

 Watson spectral color vision apparatus was used. The results 

 for the two birds used differed and indicated that the values for 

 these two wave lengths might be very different for the two 

 birds. 



Fishes. — One of the best papers published during the year is 

 von Tschermak's excellent review of the results of his own investi- 

 gations and those of others on the vision of fishes (29). Since 

 the article itself is a summary it is difficult to characterize it. 

 It treats of the physical conditions which affect vision in water, 



