208 DIGESTION. [CHAP. xxiv. 



matters, and they became softened by admixture with the fluids 

 of the stomach and appeared partially dissolved. 



Boiled starch, in Tiedemann and Gmelin's experiments,, underwent 

 solution, and then did not exhibit its characteristic blue colour with 

 iodine. In a dog, killed five hours after a meal of boiled starch, 

 the contents of the stomach underwent no change of colour with 

 iodine, .but appeared charged with sugar and with a kind of gum of 

 starch (dextrine). In another dog, similarly fed, and killed three 

 hours afterwards, the starch which was dissolved did not react in 

 the usual manner with iodine, but some portions not yet dissolved 

 did exhibit the characteristic reactions. It would seem that imme- 

 diately the starch becomes dissolved by the gastric fluid it loses its 

 characteristic property of forming the blue iodide of starch.* 



In the artificial digestion of starch, with the mucous membrane 

 of the human stomach, we have not succeeded in producing any 

 change in the starch : it still evinced its usual reaction with the 

 iodine test. We have, however, found that starch digested for 

 some time in this way evolved a peculiar sour smell like that of 

 cheese. 



Bouchardat and Sandras report, respecting the influence of 

 stomach-digestion upon starch and upon amylaceous elements, dif- 

 ferently from Tiedemann and Gmelin. They state that they have 

 been unable to obtain any evidence of the conversion of starch into 

 sugar ; that neither by fermentation, nor by the polarizing appa- 

 ratus of M. Biot, have they succeeded in procuring any indication 

 of the existence of sugar in the digested substances ; and they were 

 equally unsuccessful in detecting the formation of dextrine. Lactic 

 acid, however, appeared to them to be formed in much larger quan- 

 tity after a meal of starch than after one of fibrine or of gluten. 

 These observers likewise state as the result of their experiments, 

 that in the human subject and in the carnivora feculent substances 

 are digested with extreme slowness, and not at all unless the 

 integument of the starch grain have been ruptured by boiling. 



Fatty or oily substances, as suet, fat, oil, butter, or wax, undergo 

 no change in the stomach, according to Bouchardat and Sandras, 

 after the lapse of some hours, and may be found in that organ un- 

 changed in the midst of other matters upon which the stomach 

 exercises a solvent action, 



This we have observed in our own experiments ; and on perusing 

 the MS. notes of the results of various experiments made thirty 



* Tiedemann and Gmelin, Eecherches sur la Digestion, par Jourdain, t. i. 

 p. 340. 



