THE MOTION OF THE CHYLE. 451 



which takes place in the stomach as a kind* of tri- 

 turation 5 . Other writers thought it was more pro- 

 perly described as fermentation ; others again spoke 

 of it as a putrefaction. Varignon gave a merely 

 physical account of the first part of the process, 

 maintaining that the division of the aliments was 

 the effect of the disengagement of the air intro- 

 duced into the stomach, and dilated by the heat of 

 the body. The opinion that digestion is a solution 

 of the food by the gastric juice has been more 

 extensively entertained. 



Spallanzani and others made many experiments 

 on this subject. Yet it is denied by the best phy- 

 siologists, that the changes of digestion can be ade- 

 quately represented as chemical changes only. The 

 nerves of the stomach (the pneumo-gastric) are said 

 to be essential to digestion. Dr. Wilson Philip 

 has asserted that the influence of these nerves, 

 when they are destroyed, may be replaced by a gal- 

 vanic current. This might give rise to a supposi- 

 tion that digestion depends on galvanism. Yet we 

 cannot doubt that all these hypotheses, mechani- 

 cal, physical, chemical, galvanic are altogether 

 insufficient. " The stomach must have," as Dr. Prout 

 says 6 , "the power of organizing and vitalizing the 

 different elementary substances. It is impossible to 

 imagine that this organizing agency of the stomach 

 can be chemical. This agency is vital, and its na- 

 ture completely unknown" (T). 



5 Bourdon, Physiol. Comp. p. 514. 6 Bridgewater Tr. p. 493 



G G2 



