76 PHILOSOPHY OF ZOOLOGY. 



Into the Intestines, and some of the lizards that were allow- 

 ed to live, voided them, toward the spring, entire and with 

 very little alteration in their structure -f*. 



The immediate cause of torpidity in reptiles has been as- 

 certained with more precision, than in the animals belonging 

 to the higher classes with warm blood. This condition 

 with them, does not depend on the state of the heart, the 

 lungs, or the brain ; for these different organs have been 

 removed by Spallanzani, and still the animals became tor- 

 pid, and recovered according to circumstances. Even after 

 the blood had been withdrawn from frogs and salamanders, 

 they exhibited the same symptoms of torpidity as if the 

 body had been entire, and all the organs capable of action. 



Cold, with these animals, is evidently the chief cause of 

 their torpidity, acting on a frame extremely sensible to its 

 impressions. During the continuance of a high tem- 

 perature, they remain active and lively; but when the 

 temperature is reduced towards 40°, they become torpid, 

 and in this condition, if placed in a situation where the 

 temperature continues low, will remain torpid for an un- 

 known period of time. Spallanzani kept frogs, salaman- 

 ders, and snakes, in a torpid state in an ice-house, where 

 they remained three years and a half, and readily revived 

 when again exposed to the influence of a warm atmosphere. 

 These experiments give countenance to those reports in 

 daily circulation, of toads being found inclosed in stones. 

 These animals may have entered a deep crevice of the 

 rock, and during their torpidity been covered with sand, 

 which has afterwards concreted around them. Thus re- 

 moved from the influence of the heat of spring or summer, 

 and in a place where the temperatvire continued below the 

 point at which they revive, it is impossible to fix limits to 



+ " Observations." p. 155. 



