50 CLASS REPTILIA. 



according to the species. Perrault has given us the following 

 explanation of the circulation of the blood in one of the fresh- 

 water tortoises : — " The right and left ventricle receive the 

 blood of the two pulmonary veins, because these veins dis- 

 charging themselves into each axillary vein, mix the blood of 

 the lungs with that of the vena cava, to carry it into the right 

 ventricle from which issues the aorta. The anterior, or little 

 ventricle, has no other vessel than the pulmonary artery, and 

 this artery, -as well as the aorta, has three sigmoid valves, 

 which hinder the blood which has issued froin the heart froni 

 re-entering there, when the ventricles come to be dilated to 

 receive the blood of the vena cava, and the pulmonary vein. 

 The aorta, on issuing from the right ventricle, is divided into 

 two branches, which form two crosses, which, before turning 

 entirely downwards, produce the axillaries, and the carotids. 

 Afterwards, the left one of these casts out three branches, the 

 first of which is distributed into all the parts of the ventricle ; 

 the second proceeds to the liver, the pancreas, the duodenum, 

 and the spleen ; the third furnishes branches to all the intes- 

 tines. The left cross then unites itself with the branch of the 

 right, and they form together but a single trunk, which 

 descends along the body of the vertebra, and gives out 

 branches to all parts of the abdomen." 



As to the rest, the circulation of tortoises is extremely slow. 

 They remain lethargized during the winter, but this lethargy 

 is merely a simple diminution of the vital force, not a sus- 

 pension of certain faculties as in the hybernating mammalia. 

 The transpiration too, of tortoises, amounts almost to nothing, 

 and the only loss of substance they sustain is by the dejec- 

 tions. It was ascertained, that at the end of six months' 

 abstinence, the only diminution of weight in a tortoise of four* 

 pounds and-a-half, was one ounce. 



The bladder of tortoises is distinguished by its size, cover- 

 ing the entire of the intestines and all the other parts of the 



