150 DIGESTION. 



the former, the relative quantities in which the two secretions are 

 present in the stomach during ordinary digestion. 



Experiments upon the lower animals, provided with gastric fistulse, 

 show furthermore that in them starch is not, in point of fact, converted 

 into sugar in the stomach. In the dog, the horse, the sheep, and the 

 ox, according to Bernard, Schiff, and Colin, the action of saliva upon 

 hydrated starch is distinct, though less rapid than that of the human 

 subject. In the gnawing animals generally it is present, and in the 

 guinea pig, according to Schiff, is more decided than in man. But 

 if a dog, with a gastric fistula, be fed with a mixture of meat and 

 boiled starch, and portions of the fluid contents of the stomach with- 

 drawn afterward through the fistula, the starch is easily recognizable 

 by its reaction with iodine for ten, fifteen, and twenty minutes after- 

 ward. In forty-five minutes it is diminished in quantity, and in one 

 hour has usually disappeared ; but no sugar is to be detected at any 

 time. Sometimes the starch disappears more rapidly than this ; but at 

 no time, according to our observations, is there any indication of the 

 presence of sugar in the gastric fluids. Bernard 1 has shown the same 

 want of transformation in the dog's stomach after swallowing a mix- 

 ture of hydrated starch with ordinary food. Briicke, 2 in dogs fed with 

 starch paste, found in the stomach more or less unchanged starch, and 

 either no sugar or only traces of it, after the lapse of from one to five 

 hours. This does not depend upon any want of power in dogs to digest 

 hydrated starch, since this substance is converted into glucose in these 

 animals with great promptitude on arriving in the duodenum, by the 

 influence of the pancreatic and intestinal juices. 



It is also an important consideration, in this respect, that the saliva 

 exerts its transforming power only upon starch which has been cooked 

 or hydrated. All observers agree that it is nearly or quite without 

 action upon raw starch, which remains unchanged in contact with it at 

 all temperatures. But in the herbivorous animals, where the salivary 

 glands are at least as fully developed and the saliva as abundant as 

 in man, the starchy elements of the food are habitually taken in 

 the raw state. Even in the ruminating animals, where the food is 

 retained, for some time after the first mastication, in the paunch, 

 unmixed with gastric juice, it does not undergo there the sugar- 

 conversion. Prof. Francis G. Smith, in a series of experiments upon 

 Alexis St. Martin, affected with a gastric fistula, in 1856, 3 withdrew 

 the contents of the stomach two and a half hours after bread had been 

 masticated and swallowed; and in the mixed fluids so obtained, he 

 detected at the end of that time unchanged starch, both by the micro- 

 scope and by the iodine test. Glucose was also found in the fluid, but, 

 as bread nearly always contains glucose, it is uncertain how much, 



1 SScre'tions Digestives. Paris, 1856, p. 159. 



2 Jahresberichte der Anatomie und Physiologie. Leipzig, 1873, p. 467. 



3 Philadelphia Medical Examiner, July and September, 1856. 



