NATURAL THEOLOGY. 237 



ties of the animal. In brutes, because the posture 

 of their neck conduces httle to the passage of the 

 aliment, the fibres of the gullet which act in this 

 business run in two close spiral lines, crossing 

 each other: in men these fibres run only a little 

 obliquely from the upper end of the oesophagus to 

 the stomach, into which, by a gentle contraction, 

 they easily transmit the descending morsels — that 

 is to say, for the more laborious deglutition of 

 animals which thrust their food up instead of 

 down, and also through a longer passage, a pro- 

 portionably more powerful apparatus of muscles 

 is provided — more powerful, not merely by the 

 strength of the fibres, which might be attributed 

 to the greater exercise of their force, but in their 

 collocation, which is a determinate circumstance, 

 and must have been original. 



IV. The gullet leads to the intestines : here, like- 

 wise, as before, comparing quadrupeds with man, 

 under a general similitude we meet v/itli appro- 

 priate differences. The valvulce conniventes, or, 

 as they are by some called, the semi-lunar valves, 

 found in the human intestine, are wanting in that 

 of brutes. These are wrinkles or plates of the 

 innermost coat of the guts, the effect of which is 

 to retard the progress of the food through the ali- 

 mentary canal. It is easy to understand how 

 much more necessary such a provision may be to 

 the body of an animal of an erect posture, and in 

 which, consequently, the weight of the food is 

 added to the action of the intestine, than in that 



