250 THE PHILOSOPHY 



tltofe maggots which are produced from the Cggs of the 

 common flefli-fly. 



Before we difmlfs this fubje£V, a few obfervatlons on that 

 power, inherent in all animal bodies, of dillblving, and con- 

 verting into chyle, every nutritive fubflance thrown into the 

 flomach, merit attention. 



In order to explain the procefs of digeftlon, fome phyii- 

 cians and phllofophers have had recourfe to mechanical force, 

 and others to chemical action. The fupporters of mechanical 

 force, maintained, that the ftomachs of all animals comminu- 

 ted, or broke down into fmall portions, every fpecies of food, 

 and prepared it for being converted into chyle. The chemical 

 phllofophers, on the contrary, fupported the opinion, that 

 the food was dilTolved by a fermentation induced by the fa- 

 liva and gaftric juices. The difputes which naturally arofe 

 from thefc feemingly oppofite theories, ftimulated the inqui- 

 ries of the ingenious, and produced feveral curious and im- 

 portant difcoveries. Reaumur, M'Bride, Stevens, Spalanza- 

 ni, Hunter, have all exerted their induftry and talents upon 

 this fubjecSl:. To give even an abridged view of their differ- 

 ent labours would be both tedious, and, at the fame time, 

 would not coincide with the defign of this work. I fliall 

 therefore confine myfelf to {orvxe refults of their experience 

 and labours. Spalanzani, who is a voluminous writer on this 

 fubjefc, relates not only the difcoveries of his predecefTors, 

 but has enriched his w^ork with numerous experiments and 

 obfervatlons made by himfelf. In his inveftigation of the 

 procefs of digcftion, and the action of the flomach, he ob- 

 ferves the following order : 



1, He tre-cits of animals witli flrong raufcular ftomachs, as 

 common fowls, turkeys, ducks, geefe, pigeons, &c. 2. Of 

 animals with ftomachs of an intermediate confiflence, as 

 crows, herons, ccc. 3. Of animals with membranous flonv- 

 rschs, as frogs, lizards, earth and water fnakes, vipers, fiflies,- 



