178 DIGESTION. 



introduced in the stomach, fasting, by the fistula ; immedi- 

 ately after, a portion of the starch was expelled again; 

 already it contained sugar. A quarter of an hour after, a 

 great deal of sugar was found in the stomach, and the paste 

 had become entirely fluid." 



There can be no doubt that the saliva, in addition to its 

 important mechanical functions, transforms a considerable 

 portion of the cooked starch, which is the common form in 

 which this principle is taken by the human subject, into 

 sugar; but it is by no means the only fluid engaged in 

 its digestion, similar properties belonging, as we shall see 

 hereafter, to the pancreatic and the intestinal juice. The 

 last-named fluids are probably more active, even, than the 

 saliva. The saliva acts slowly and imperfectly on raw 

 starch, which is hydrated in the stomach and digested main- 

 ly by the fluids of the small intestine. In all probability, 

 the saliva does not digest all the hydrated starch taken as 

 food ; the greater part passing unchanged from the stomach 

 into the intestine. Those who attribute only a mechanical 

 function to the saliva draw their conclusions entirely from 

 experiments on the lower animals, particularly the carniv- 

 ora ; and it is evident that such observations cannot be strictly 

 applied to the human subject. 1 



The principle which is specially active in the digestion of 



1 In the herbivora, the chemical action of the saliva is much more important 

 than in the carnivora. In the report of a commission of the Academy of Sci- 

 ences, in 1845, composed of Magendie, Rayer, Payen, and others, the following 

 interesting facts were developed concerning the mixed saliva of the horse : 



" This saliva was obtained in a state of purity by causing a horse, that had 

 an opening into the O3sophagus, to eat bran washed, first with cold water, and 

 afterward with boiling distilled water. * * * * 



" The bran thus prepared was given to the horse, who chewed it, moistened 

 it with saliva, and swallowed it ; and it is the liquid pressed from the masses 

 and filtered which has been studied under the name of the mixed saliva. * * 



" Like the human saliva taken from the mouth, the mixed saliva of the horse 

 transforms starch-paste instantly into sugar at 104 Fahr. At the temperature 

 of 104, it has a slow but sensible action on raw starch and on coagulated albu- 

 men." Compos Rendus, Paris, 1845, pp. 903, 904. 



