REAUMUR 249 



light emitted by certain mollusks, and especially by 

 the Pholadidae. It will be seen that Reaumur was by no 

 means unacquainted with physiology. Experiments as 

 ingenious as they were decisive, showed him in 1752 

 the singular difference in the digestive organs of birds 

 of prey, whose stomach acts on the food only by means 

 of a solvent liquid, and those of grain- eating birds, in 

 which a very powerful muscular gizzard exerts a pressure 

 sufficiently great to crush and pulverise extremely hard 

 substances." 



[Reaumur's experiments on the digestion of birds,^ are 

 memorable in the history of physiology. Seeking to 

 clear up the question whether food in the stomach is 

 merely triturated, or whether it undergoes a chemical 

 change, and in that case whether the change most 

 resembles solution or putrefaction, he made a number 

 of ingenious experiments on a captive kite. Small 

 metal tubes, whose ends were closed by fine gratings, 

 were filled with pieces of meat and offered to the bird in 

 its food. When the kite, according to custom, rejected 

 the tubes with other indigestible matter, the contents 

 were carefully examined. The meat, though protected 

 against trituration, was found to be partly dissolved ; it 

 exhibited no signs of putrefactive change. Even frag- 

 ments of bone were more or less corroded. Vegetable 

 matter on the other hand was hardly acted on. The 

 tubes contained besides the remains of food a yellow 

 fluid of bitter taste ; large quantities of this were col- 

 lected by tubes filled with pieces of sponge, which could 

 l)e squeezed after rejection from the stomach. With 

 this fluid R(^aumur attempted artificial digestion, and 

 though complete success was not achieved he was at 

 least able to show that gastric digestion differs altogether 



^M^m. Acad. Sci., 1752. 



