82 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



He also found that the green state could be produced in three 

 ways, namely, by subjecting the animals to the absence of light, 

 by inhibiting the blood circulation, and by cutting off the nerve 

 supply. 



Inhibiting the circulation, he found, was a more important 

 factor than cutting off the nerve supply, in that it brought about 

 more rapidly the green state and, furthermore, when both factors 

 acted simultaneously, still greater rapidity in change occurred than 

 when either one acted alone. 



Carlton believes that the green state represents the unstimulated 

 state of the skin, which is suggested by the fact that ether narcosis, 

 nicotin poisoning, and death are associated with the green state. 

 The brown state, he believes, is brought about by stimulation of 

 the nerve endings and represents "the state maintained through 

 tonus established by the s>Tn pathetic nerves and dependent upon 

 stimulation of the nervous end organs in the skin by light." 



Parker and Starratt, repeating Carlton's experiments on the 

 rapidity of change from one color state to another, obtained results 

 that were not uniform and found that changes would occur more 

 rapidly on one day than on another and even at different times 

 during the same day. 



By means of a constant temperature apparatus which could be 

 illuminated at 115 candle-meters and at the same time brought 

 from io°C. to so°C., they found the average length of time at 

 various temperatures at which either the brown or green state 

 could be produced from the opposite color state. They found that 

 at io°C., the skin remained brown in either light or dark, but as 

 the temperature was raised to 2o°C., the animals placed in the 

 dark became green in 19.66 minutes. At 25°C., under the same 

 conditions, the change took place in 13.23 minutes; at 3o°C., it 

 took 10.93 minutes; at 35°C., 15.48 minutes. At 4o°C. to 45°C., 

 the skin remained greenish gray to green in both light and 

 darkness. 



On the other hand, when green lizards were placed in the light 

 at 2o°C., the brown state was brought about in 4.23 minutes; at 

 25°C., 3.52 minutes; at 3o°C., 3.13 minutes, and at 35°C., 2.8 

 minutes. 



These investigators believe that at intermediate temperatures, 

 namely, between 2o°C. and 3S°C., light is the controlling factor 

 but that temperature is effective over this range is evident in that 

 it may influence the rate of change. 



