18 ORGANIZATION OF REPTILES. 



with excretory ducts, is found in all Reptiles; and is of smaller proportionate size 

 than in the Mammalia or Birds. In the Chelonia it is intimately connected with 

 the liver, being almost concealed by the right lobe; while in the Serpents it is 

 completely separated from it. The admixture of the bile with the alimentary 

 substance in the small intestine, produces a very important change in the nature 

 of the aliment received into the stomach. 



A pancreas has been observed in most Reptiles; it is situated near the junction 

 of the stomach with the small intestines, and is a smooth glandular mass, similar 

 in structure to that of the Maimnalia, but varying greatly in figure and the number 

 of its excretory ducts. In some there is but one, while in others we find as many 

 as three ducts opening into the small intestines. 



A spleen exists in all vertebrated animals, the type of its form being the same 

 as in the Mammalia; and we find a successive diminution in its developement to 

 the Fishes, where it is least perfect. It is of small size in the Reptiles, varies 

 much in position, and is often found far removed from the stomach; we find it 

 in some on the right side, in others on the left, but most frequently it is placed 

 in the mesial line, or a little to the left of it.* From its being so much diminished 

 in size, it would seem to follow that the organ is of less importance to this class of 

 animals than to the Mammalia.t 



Physiology of Digestion. — The absence of proper organs of mastication and 

 insalivation, together with the short alimentary canal and simple form of stomach 

 in Reptiles, denote their carnivorous habits. As there is no mastication to break 

 down the food, no trituration in the stomach to facilitate digestion, the process 

 being done in most of them by the action of the gastric juice, or the stomach alone 

 on the food, it follows tliat digestion must be very slow. In some, the food remains 

 for days in the stomach; we have seen a Water-snake (Coluber erythrogaster) 



*Dumeril, Hist. Nat. des Rept., torn. i. p. 143. 

 t Cuvier, Legons d'Anat. Comp., torn. iv. p. 57. 



