BEHAVIOR OF VERTEBRATES 417 



orientation is complete though this does not necessarily do away 

 with the effect of intensity." 



Hess had previously shown that amphibian vision is like 

 human, i.e., under dark adaptation the long wave end is short- 

 ened and the region of greatest brightness is pushed toward the 

 shorter wave end. Himstedt and Nagel had confirmed this 

 conclusion by a study of the action currents of the eye. Now 

 Babak (2), by means of the breathing method described in this 

 journal, 1913, Nov. -Dec, shows the same thing but adds addi- 

 tional curious facts. By this method the stimulating effect of 

 V seemed extraordinarily great. Even in weak intensities it 

 was stronger than the G. He says that the filter apparatus was, 

 of course, not absolute, yet undeniably R and V equal in bright- 

 ness had different stimulus values. R had a very weak, V a 

 very strong influence on the breathing activity. W light had a 

 slighter stimulus value than V. It seemed to be the resultant 

 of the RG and V effects. He thinks that this result is probably 

 caused by the ultra-violet rays while the long thermal rays have 

 a practically negligible effect. 



Fishes. The facts as to the color vision of fish are still con- 

 troverted points in which C. Hess (26, 27) and von Frisch (17, 

 18, 19, 20, 21) are the principal opponents. A considerable 

 number of papers have appeared which will be discussed together 

 since nothing is gained by separate reviews and since in each 

 new article the whole argument is repeated with additional 

 matter. To von Frisch the chromatic adaptation of fishes to 

 the color of the background against which they lie is an evidence 

 of color vision. He discusses this adaptation at length and shows 

 how it is due to the expansion and contraction of the pigment 

 cells. This reaction, he believes, depends upon the nervous system 

 and he finds a center in the brain anterior to the cord whose 

 stimulation will cause such changes. The study is continued by 

 means of nerve section, histological methods, etc. The reaction 

 to yellow ground was only found in those fishes which could 

 see. Phoxinus laevis L. reacted to yellow ground by an expan- 

 sion of R and Y pigment cells but to G, Blue, or V ground in 

 the same way as to gray. This reaction was, therefore, due to 

 brightness. He used blind Crenilabrus roissali, five groups of 

 five fish each, and had them four weeks under experimentation. 



