OF DIGESTION. 229 



361. To determine the time requisite for digestion 

 i is evidently impossible, if we consider how it must vary 



according to the quality and quantity of the ingesta, 

 the strength of, the digestive powers, and the more or 

 less complete previous mastication. 



During health, the stomach does not transmit the 

 digestible parts of the food before they are converted 

 into a pulp. The difference of food must therefore 

 evidently cause a difference in the period necessary for 

 digestion.* It may, however, be stated generally, that 

 the chyme gradually passes the pylorus between three 

 and six hours after our meals. (C) 



362. The pylorus f is an annular fold> consisting not, 

 . like the other rugae of the stomach, of merely the vil- 

 lous, but also of fibres derived from the nervous and 

 muscular, coats. All these, united, form a conoidal 

 opening at the termination of the stomach, projecting 

 into the duodenum, as the uterus does into the vagina, 

 and, in a manner, ;embraced-b.y it. i . , i 



NOTES. 



(A) Seven grains of the inner coat pf a calf 's stomach were 

 found by Dr .Young to enable water poured upon it to coagulate 

 6857 times its weight of milk. 



* See J. Walaetis, De Motu Chyli. p. 534. LB. 1651. 8vo. 

 f H. Palm. Levelling, Dissert, sistens Pylorum, Sfc. Argent. 1764. 4to. 

 Reprinted in Sandifort's Thes. Vol. iii. 



