J^'O 



THE PHILOSOPHY 



The next feries of experiments were made upon animals with 

 what Spalanzani denominates intermediate (lomachs between the 

 mufcular and membranous, as ravens, crows, herons, Sec. The pow- 

 er and adtion of thefe intermediate ftomachs are fuperior to thofe 

 of the membranous kind, but greatly inferior to thofe of the muf- 

 cular. The tin tubes, or balls, which pigeons and turkeys foon flat- 

 ten and disfigure, remain unaltered in the ftomach of crows. Their 

 gaftric mufcles, however, are by no means inert. Though they are 

 unable to comprefs or diftort tin tubes, they are capable of produ- 

 cing this efFedt upon thin tubes of lead. Birds whofe ftomachs are 

 of an intermediate kind, with regard to the thicknefs and ftrength 

 of their mufcular coats, may be denominated omnivorous. They eat 

 grafs, herbs, grain, and flefh of every kind. When we make expe- 

 riments, upon the digeftive powers of gallinaceous birds, the animals 

 muft be killed before we can learn what effeds have been produced 

 on the fubftances inclofed in the balls or tubes. Bur, on crows and 

 ravens, experiments of this kind may be repeated as often as we 

 pleafe, without deftroying a fingle individual. Subftances which 

 they are incapable of digefting, as metallic tubes, they have the 

 power of difgorging, or returning by the mouth, in the fame man- 

 ner as falcons, and other birds of prey, throw up the feathers and 

 hair of the animals they have devoured. In birds of prey, this vo- 

 miting is commonly performed every twenty-four hours; but, in 

 crows, it happens at leaft every nine, and not unfrequently every 

 two or three hours.. 



Spalanzani, as in the former experiments, thruft down perforated 

 tubes, filled with different fubftances, into the ftomachs of crows. 

 Thefe tubes were uniformly thrown up by the animals in a few 

 hours. When the tubes were filled with entire grains, as wheat or 

 beans, he found that the gaftric juice, though the tubes, by being 

 repeatedly forced down, continued in the ftomach for the fpace of 



3 ^o"y- 



