GASTRIC FLUID DISCOVERED. 23 



putrefaction : Galen, to its decomposing it by a peculiar 

 accumulation of heat, during the time of digestion : and 

 Macbride and Pringle long afterwards, to the action of 

 fermentation ; thus combining the two causes assigned 

 by the Greek writers. Grew and Santarelli embraced 

 the doctrine of a concoction, by the various juices that 

 are poured into the stomach from the liver, the spleen, 

 and other organs ; while Pitcairn, and all the mecha- 

 nical physiologists, contended that it was accomplished 

 by a process of trituration, occasioned by an enormous 

 mechanical pressure of the muscular coat of the stomach 

 upon its alimentary contents, which they were fanciful 

 enough to calculate, the minutias of the computation 

 being detailed in some of their works, to act with a 

 force exceeding 117,000 pounds, assisted at the same 

 time in its gigantic labour, by an equal force derived 

 from the surrounding muscles. 



Reflecting men, however, were still dissatisfied. Each 

 of these theories was found to be encumbered with 

 difficulties of its own, while all of them were alike 

 incompetent satisfactorily to explain the fact for which 

 they were invented. At length Cheselden threw out 

 the fortunate hint, that possibly digestion might be 

 accomplished by means of some peculiar solvent, 

 secreted by one or other of the digestive organs : 

 and he directly pitched upon the saliva, or the fluid 

 secreted by the salivary glands. 



The hint was eagerly seized and followed up by 

 Haller, Reaumur, Spallanzani, and others; and though 

 it was at once seen that Cheselden was under a mistake 

 as to the particular fluid, yet a fluid of a most won- 

 derful solvent power was soon detected, secreted from 

 the internal surface of the stomach itself, and its 



