6 On the Action exercised by Caloric 



would take place during a continued privation of the ca- 

 loric necessary for the state of life. This might serve to 

 explain whether the real death of animals rendered torpid 

 by cold arises from the want of that caloric necessary to the 

 state of life, or rather from the manner in which they are 

 deprived of it. I thought it necessary also to ascertain what 

 would take place by rendering torpid and reviving alter- 

 nately the animals, or by making them to pass slowly from 

 heat to cold, and from cold to heat, or rapidly from heat to 

 cold. 



Being desirous of subjecting animals to these three dif- 

 ferent circumstances, I employed ants. It is well known 

 that these insects pass the whole winter in a state of torpor 

 in their hills : those which I subjected to experiment were 

 inclosed in the large trunk of an oak, where, notwithstand- 

 ing the severe cold, they were not in a state of great torpor. 



I exposed to the north during winter ninereen of these 

 ants in a flask in such a manner that they should receive 

 none of the sun's rays. During the warmest hours, the 

 thermometer indicated -f- 5° and — 2° for the mean cold. 

 These animals, in consequence of the continued cold, re- 

 mained in a state of perfect torpor during seven days. On 

 the eighth day I resolved to recal them tq, life by subjecting 

 them gradually to the influence of heat; and I had the plea- 

 sure to see them all return to life. 



At the same time I exposed nineteen others to the open 

 §outb, where the highest temperature in the sun was -f 2.5°, 

 while in the shade it was only 4- 5° or + 6°, and the great- 

 est mean cold — 2 P . In this manner the ants were alter- 

 nately and slowly thrown into a state of torpor at sunset, 

 and revived at sunrise. On the eighth day I exposed them 

 gradually to heat; and recalling some of them in this man- 

 ner to life, I found eight of them dead. By these facts it is 

 seen that in the first experiment the privation of the caloric 

 necessary to the state of life was not fatal to ants though, 

 continued for a considerable time, but rather the slow pri- 

 vation of it which they daily experienced. 



Before I proceed to other facts I must take notice of the % 

 state of weakness into which living beings fall after the 

 state of torpor. It is to facts of this kind that I reduce the 

 ingenious experiments of the celebrated Hunter, who ob^ 

 served that blood, eggs, &c. freeze, more readily after they 

 have been once frozen. 



Not being well acquainted with the method of preserving 

 ants alive, I had left them all exposed to the open south 

 in a flask, hoping that the beneficent rays of the sun would 



£ preserve 



