458 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Nevertheless, since all our experiments had been carried on with more 

 or less change of temperature, it was necessary to check this before any 

 sound conclusions could be drawn as to other factors. On December 30, 

 with the temperature in the box varying from 22° C. just before the 

 experiments were begun to 27° at the close of them, the average time of 

 twenty records at various intermediate temperatures was 15.58 minutes, 

 while at 27° it was 12 minutes. Therefore, notwithstanding the opinion 

 of many investigators that temperature plays little or no part in the 

 color changes of lizards and other lower vertebrates, we determined to 

 test the influence of heat on Anolis, and the results obtained are given 

 on the following pages. 



II. Apparatus. 



The apparatus used consisted of a wooden, upright, constant- 

 temperature box, 70 cm. high, 35 cm. deep, and 40 cm. wide. The 

 front of this box was in the form of a tight-fitting door, near the middle 

 of which was a small glass window so placed that observations could be 

 made from the outside without opening the box to the air. This window 

 was provided with a light-proof shutter. 



The interior of the box was lined with black cloth, and on the bottom 

 was placed a cylindrical metal water-chamber 10 cm. high and 32 cm. in 

 diameter. This held about 8 litres of water, which could be kept at 

 constant temperature by a slow flow through an inlet and outlet con- 

 nected with a water supply outside the box. On the inside of the back 

 of the box, 45 cm. above the top of the water-chamber, was placed an 

 electric incandescent lamp, which could be controlled from the outside 

 by a key. About 10 cm. below this was inserted in the box a wooden 

 cross partition carrying an oblong flat-bottomed glass dish. This con- 

 tained distilled water 3 cm. deep, and served as a heat screen when the 

 lamp was lighted. As the air of the small upper chamber which con- 

 tained the lamp soon became heated when the lamp was lighted, a 

 ventilating system was provided. This consisted of a lower inlet pipe 

 and an upper outlet pipe, both of which had elbows in them to prevent 

 the entrance of light. When the lamp was lighted a temperature any- 

 where between 10° and 50° C., and constant to within half a degree or 

 so, could be easily maintained at the level of the top of the water- 

 charaber. This was shown by a thermometer inserted through the wall 

 of the box at this point. 



It was found on trial that the nervous states of the lizards had much 

 to do with the rate of the color changes, and to get uniform records it 



