PHYSIOLOGY. 187 



the vegetable matter of it begins to be changed to the nature of 

 animal, and the oily parts of the whole begin to be united with 

 the watery. But these changes by solution, assimilation, and 

 mixture, require to be separately considered. 



CCXXX. The solution here, as in other cases, may be as- 

 sisted by the mechanical division of the solid matter, by the 

 agitation of the dissolving'mass, and by the application of heat ; 

 and, with these assistances, the solution must be performed by 

 the application of a proper menstruum. 



CCXXXI. The division of the solid is sometimes assisted 

 by a previous cookery, and commonly by the manducation we 

 have mentioned ; but the human stomach does not seem by any 

 mechanical powers to contribute to this. It gives only a mode- 

 rate agitation, which, in any case, contributes little to mechani- 

 cal division. 



CCXXXII. The degree of heat applied here, being that of 

 the common temperature of the human body, may assist the 

 solution ; but it is of no considerable power, and no assistance 

 is got from any closeness of the vessel which occurs here. 

 Upon the whole, the assistances applied here are not considera- 

 ble, and the speedy solution that takes place must be chiefly 

 owing to the power of the menstruum. 



CCXXXIII. The menstruum that appears here is a com- 

 pound of the liquid matters taken in, of the saliva, and of the 

 gastric liquors ; but in all or any of these, we do not readily 

 perceive any considerable solvent power ; nor, by any artifice 

 in employing these out of the body, can we imitate the solu- 

 tions performed in the stomach. " What may be the power 

 of the gastric menstruum, or the causes of its different power 

 with respect to different substances, is not well ascertained ; but 

 we now know that it is different in different animals, insomuch 

 that in many carnivorous animals it has little power with respect 

 to vegetable matters ; and that in phytivorous animals it has 

 little power with respect to animal substances. (See Steven's 

 De Alimentorum Concoctione, Edin. 1777-) 



" Although in the human stomach the gastric menstruum 

 seems commonly to have power with respect to both animal and 

 vegetable matters, it is, however, probable, that upon different 

 occasions its power is in a different degree with respect to these 



