OF NATURAL HISTORY. 225 



the food was dlffblved by a fermentation induced by the faliva and 

 gaftric juices. The difputes which naturally arofe from thefe feem- 

 ingly oppofite theories, ftimulated the inquiries of the ingenious, and 

 produced feveral curious and Important difcoveries. Reaumur, 

 M'Bride, Stevens, SpalanzanI, Hunter, have all exerted their indufiry 

 and talents upon this fubjed:. To give even an abridged view of 

 their different labours would be both tedious, and, at the fame time, 

 would not coincide with the defign of this work. I fhall therefore 

 confine myfelf to fome refults of their experience and labours. 

 Spalanzani, who is a voluminous writer on this fubje(fl:, relates not 

 only the difcoveries of his predeceffors, but has enriched his work 

 with numerous experiments and obfervations made by himfelf. In 

 his inveftigation of the procefs of digeflion, and the afliion of the 

 ftomach, he obferves the following order: 



I. He treats of animals with ftrong mufcular ftomachs, as com*- 

 mon fowls, turkeys, ducks, geefe, pigeons, &c. 2. Of animals with 

 ftomachs of an intermediate confiftence, as crows, herons, &c. 

 3. Of animals with membranous ftomachs, as frogs, lizards, earth 

 and water fnakes, vipers, fifhes, fheep, the ox, the horfe, the owl, 

 the falcon, the eagle, the cat, the dog, man, &c. 



With regard to birds which are furnlflied with mufcular ftomachs, 

 or gizzards, Spalanzani, in imitation of Reaumur, procured fmall glafs 

 and metal balls and tubes, perforated with many holes. Thefe he 

 filled with different kinds of food, and forced them down the 

 throats of common fowls, turkeys, &c. He filled balls with bar- 

 ley, or other grains, in their entire ftate, and allowed them to re- 

 main in the ftomachs of ducks, turkeys, and other fowls, for tvyen- 

 ty-four, and, in fome cafes, for forty-eight hours. He then killed 

 the animals, took the balls out of their ftomachs, and, after examin- 

 ing the grains attentively, he could not difcover that the gaftric juice, 

 t I' f to 



