1903 Reptile Studies 297 



Reptile Studies. 



By Gerald Leighton, M.D., F.R.S.E. 



X. The Process ov Digestion in Serpents. 



Curtain appearances that I have from time to time 

 observed in snakes which I have dissected, lead me to 

 think that the process of digestion in these reptiles is 

 inadequately understood and described. I refer here to the 

 mechanical part of the process, not the physiological action 

 of the digestive fluids. I am satisfied that in the mechanism 

 of digestion we have to deal with a process undescribed in 

 text-books, and which is briefly now dealt with. 



Serpents arc, of course, animals which swallow very 

 large articles of diet, and swallow them whole, there being 

 nothing in the shape of mastication in ophidian digestion. 

 Such diets often consist of frogs, newts, fish, water-voles, 

 mice, rats, birds, lizards, and even other snakes. All of 

 these are swallowed entire, the enormous capacity of the 

 ophidian jaw for dilatation allowing of the passage of this 

 food into the gullet. In order to understand what takes 

 place after this, it must be stated that the alimentary canal 

 in serpents is divided into three portions, best termed the 

 fore-gut, the mid-gut, and the hind-gut. These three parts 

 are often spoken of in books as the gullet, stomach, and 

 intestine respectively. The gullet is long, widely distensible, 

 with very thin elastic walls, and is non-digestive in function. 

 In the case of the adder it is 9 inches long in an average- 

 sized specimen. It ends abruptly at a constriction, and at 

 this point the walls become thick and strong, and not so 

 distensible. Here commences the mid-gut, an organ which 

 is surprisingly small. In adders it measures 2} to 3 

 inches in length. In an Australian black snake 4 feet 

 lung this mid-gut was 5 inches in length. If opened, its 

 walls are seen to be thrown into longitudinal folds or 

 rugae, thick and vascular. At the posterior end is a second 

 constriction. The question is doubtful whether the con- 

 striction at the anterior end corresponds with the cardiac 

 end of the mammalian stomach, and that at the posterior 



