172 Sylvius and his Pupils. [lect. 



" ferment, whereas in the whole construction of the stomach 

 " nothing peculiar is observed which would render the elabora- 

 " tion of such a special agent likely." 



But even admitting the existence and action of various 

 ferments, the physiology of digestion is according to Stahl 

 still far from being explained. 



"Although the medical schools, following van Helmont, 

 " rightly judge, as a general conclusion that the resolution 

 " of food takes place after the fashion of a fermentation, the 

 " particular way in which it occurs is involved in almost in- 

 " superable difficulties. The chief of these consists in this that 

 "not only the fermentation of fermentable things takes place 

 "far more rapidly in the stomach than outside it, but also, 

 "things subject outside the body to no fermentation at all, 

 " unless it be that of putrefaction, undergo as it were a special 

 " kind of fermentation in the stomach, and do not follow that 

 " kind to which under other circumstances they are prone, but 

 "are overtaken and overcome by this digestive fermentation. 

 " Then there is the specific character which is imposed on the 

 " digested material as is seen in the differences which exist in 

 " even the crude chyle, or the milk of different animals living 

 " on exactly the same food. 



"In any case the fermentation which takes place in the 

 " alimentary canal is not an ordinary fermentation such as 

 "occurs in a merely compound not-living body, but a most 

 " special character is impressed on the change, impressed by 

 "the energy of the soul." 



Stahl's teaching, in fact, was briefly this : 



Learn as much as you can of chemical and physical pro- 

 cesses, and in so far as the phenomena of the living body 

 exactly resemble chemical and physical events occurring in 

 non-living bodies, you may explain them by chemical and 

 physical laws. But do not conclude that that which you see 

 taking place in a non-living body, will take place in a living 

 body, for the chemical and physical phenomena of the latter are 

 modified by the soul. The events of the body may be rough 

 hewn by chemical and physical forces, but the soul will shape 

 them to its own ends, and will do that by its instrument, motion. 



