54f CLASS REPTILIA. 



from their lungs being inflated with an unusual quantity of 

 air, from their having lost by the dessication of the carapace 

 (according to the observation of Lacepede) at least one-sixth 

 of their weight, and their specific gravity being inconsiderable 

 in proportion to the volume of water which they displace. 

 Accordingly, they are observed, on entering the water, to 

 discharge from their mouth and nostrils, in bubbles, the super- 

 abundant air of which they must get rid before they can sink 

 to the bottom. 



The brain of tortoises is extremely small, and appears to 

 be scarcely necessary to their existence. The experiment of 

 Redi is well known, who removed the brain from a land tor- 

 toise, which lived six months after the operation. 



If, as every fact with which we are acquainted on the sub- 

 ject appears decisively to prove, the intelligence of the animal 

 is in proportion to the capacity of the cranium, the tortoises 

 must be placed among the most irrational and inert of the 

 living tribes. The range of their sensations may be said to 

 be confined to the strictest limits of necessity, or, in other 

 words, merely to what is indispensable for the purposes of 

 self-preservation and reproduction. All of them, whether 

 observed in captivity or in freedom, have a stupid, hebetated 

 physiognomy. It is said, that at the epoch of their amours, 

 they assume somewhat more of a lively character, and that 

 the males, according to the custom of most animals, fight 

 furiously for the possession of the females. 



*' Causa teterrima belli." 

 But at other periods they wrap themselves up in apathy, and 

 remain inert until some severe evil obliges them to make use of 

 their formidable beak and claws. M. Bosc says, that he has 

 frequently removed the breastplate from a living tortoise, and 

 the animal exhibited no uneasiness, nor made any effort of 

 resistance. It was not until they experienced the utmost 

 degree of pain, in the removal of the internal organs, that 



