[cameron-brownlee] temperature AND THE FROG 71 



and spring frogs from Illinois were used. It must be emphasised 

 that the results obtained only apply necessarily to the species men- 

 tioned at the time of year stated. 



Before passing to the results obtained in the three series of ex- 

 periments, it may be noted here that Lord Lister's experiment was 

 repeated in a single case with a specimen of R. pipiens. The frog 

 was held in the hand for 20 minutes. Breathing ceased after about 

 10 minutes; there were convulsive movements after 15 minutes. 

 At the end of 20 minutes the animal was quite unconscious, but the 

 heart was beating rapidly and strongly. The animal recovered in 

 10 minutes. Hence such treatment is not necessarily fatal in the case 

 OÎ R. pipiens. 



I. EXPERIMENTS ON THE INTACT ANIMAL, IMMERSED IN WATER. 



The water in a small thermostat was slowly raised from room 

 temperature to the temperature desired, which was then maintained 

 by successive additions of warm or cold water, the water being rapidly 

 stirred. The frog was completely immersed. A small thermometer 

 was passed through the gullet into the abdomen, and the temperature 

 recorded taken as the frog's internal temperature. The frog was 

 bound loosely to prevent movement. The thermometer was cor- 

 rected against a certificated standard, and the temperatures given 

 throughout the paper are correct to within 0- 1°C. 



It will be shown in another communication that frogs can re- 

 main immersed in cold water for several weeks without fatal results. 

 At the temperatures employed in the following experiments the oxy- 

 gen content of the water is not greatly lessened, and the fatal results 

 are not therefore to be attributed to any deficiency in oxygen-res- 

 piration (which during such immersion takes place through the skin). 



In a number of preliminary experiments the temperature of the 

 water was gradually raised to a maximum and the frog then immediate- 

 ly removed, so that exposure to such. maximum temperatures was but 

 momentary. Under such conditions, when the time of heating 

 from room temperature was from 25 to 30 minutes an internal tem- 

 perature of 39-5° was completely fatal (all tissues killed). The cor- 

 responding external temperature was 44°. An internal temperature 

 of 38-5° (external 42°) was fatal in two instances out of three though 

 the heart recommenced beating and the muscles were not killed. 

 The third animal recovered after a long interval (it was left overnight, 

 and the exact time of recovery was not recorded). In experiments 

 in which the internal temperature attained was 37-5° (2), and 37°, 

 the animal recovered in an hour or less. 



