MOVEMENTS IN THE VISUAL CELLS 147 



of the medium irrespective of acti\ities at the surface of the 

 body. 



The apparatus for this verification consisted merely of a 

 large battery jar, a sheet of coarse wdre gauze and suitable weights. 

 The jars were filled with water to within a quarter of a centimeter 

 of the top, and the gauze, held in place by weights, served as a 

 cover. This device worked in the following manner. Animals 

 coming to the surface to breathe could only get their nostiils 

 above water, the rest of the head and bod}' remaining submerged, 

 hence, in a short time the body temperature of the frog neces- 

 sarily approximated that of the surrounding medium. 



At 3°C\ the body temperature of the animal quickly fell, th(> 

 respiration rate was reduced until it practically ceased and the 

 bodily activities diminished until the frogs, for the most part, 

 remained quietly at the bottom of the jar. although some animals 

 would occasionally swim to the surface to breathe. At33°('., 

 on the contrary, the frogs were very active and had to return at 

 shoi't intervals to the surface, where they would sometimes remain 

 for several minutes clinging to the netting. 



A series of experiments was performed both in darkness and 

 in light. In the dark nothing new was learned beyond the con- 

 ditions already described. In the light, the first experimeni 

 showed a state of extreme pigment expansion at 3°C., which 

 was comparable to that of Ameiurus under similar conditions. 

 The other trials, at 16°C. and 33°C\, on the contrary, showed the 

 pigment uniformly distributed. Another experiment, a short 

 time after, gave the same result at 3°C\ but not so decisively. 

 The possibility of discovering a similarity in the pigment re- 

 sponses of frogs and fishes iii the Hght, led me to repeat these ex- 

 periments many times without, howe^^er, again obtaining similar 

 results. 



If extreme jiigment expansion occurred at 3°C. it would be 

 interesting from another standpoint since Herzog reported 

 a similar condition, in darkness, at the highest temperatures 

 which these animals can withstand. 



Occasionally during experiments both in light and in dark- 

 ness, an anomalous condition arose whereby the distribution 



