298 The Field Naturalist's Qtcarterly November 



end with the pyloric constriction, or not. It does not, 

 however, concern my present point. The hind-gut, of 

 course, runs from the posterior end of the mid-gut to the anal 

 orifice, the terminal portion being a short straight rectum. 



The parts played by these three portions of the tract in 

 the mechanism of digestion are as follows : — 



(a) The gullet holds the food swallowed until such time 

 as the reptile begins to digest. No change takes place in 

 the food as long as it remains in this fore-gut. 



(/;) The mid-gut digests the food as it passes into it from 

 the fore-gut. 



(r) The hind-gut absorbs the digested food, acts on such 

 as has not already been digested, and absorbs that, and 

 passes on the small amount of faecal matter which escapes 

 from a snake. 



At first sight it might appear that there is nothing 

 unusual in this, but that is not so. The curious part of 

 the process is that stated in the words underlined, namely, 

 that the food is digested in the mid-gut as it passes into 

 that organ from the gullet. In other words, the food does 

 not pass from the gullet into the stomach or mid-gut and 

 then undergo digestion, which is the usual method, but is 

 held by the constricting muscles at the entrance, passes in 

 gradually, becoming disintegrated as it does so. The 

 evidence that I bring forward in support of this statement 

 is as follows : — 



It is, of course, well known that animals swallowed 

 alive by snakes may and do survive their incarceration in 

 the gullet, provided that that incarceration is not of too 

 long duration. A frog has been known to remain for 

 twenty minutes in the gullet of T. natrix, and on being 

 disgorged exhibit no ill effects. I have repeatedly caused 

 snakes to disgorge frogs which they have swallowed, and 

 seen the same thing. This is very easily done by stroking 

 the belly of the snake after the frog has passed into the 

 gullet. Indeed, merely picking up the reptile is often 

 sufficient to bring about the ejection of recently swallowed 

 food. Then the dissection of a large number of adders and 

 ring-snakes has shown me many instances in which the 

 food had been in the gullet long enough to die ; but in no 



