114 DIGESTIVE PROCESS. 



accomplished in the stomach, acts on the food. The 

 insoluble matters become soluble, they are digested. 



It is certainly remarkable, that hard-boiled white 

 of egg or fibrine, when rendered soluble by certain 

 liquids, by organic acids, or weak alkaline solutions, 

 retain all their properties except the solid form (cohe- 

 sion) without the slightest change. Their elementary 

 molecules, without doubt, assume a new arrangement ; 

 they do not, however, separate into two or more groups, 

 but remain united together. 



The very same thing occurs in the digestive process ; 

 in the normal state, the food only undergoes a change 

 in its state of cohesion, becoming fluid without any 

 other change of properties. 



The greatest obstacle to forming a clear conception 

 of the nature of the digestive process, which is here 

 reckoned among those chemical metamorphoses which 

 have been called fermentation and putrefaction, consists 

 in our involuntary recollection of the phenomena which 

 accompany the fermentation of sugar and of animal sub- 

 stances (putrefaction), which phenomena we naturally 

 associate with any similar change ; but there are num- 

 berless cases in which a complete chemical metamor- 

 phosis of the elements of a compound occurs without 

 the smallest disengagement of gas, and it is chiefly these 

 which must be borne in mind, if we would acquire a 

 clear and accurate idea of the chemical notion or con- 

 ception of the digestive process. 



All substances which can arrest the phenomena of 

 fermentation and putrefaction in liquids, also arrest di- 



