130 DIGESTION. 



observers, that this property of the saliva was rather an accidental 

 than an essential one; and that, although starchy substances are 

 really converted into sugar, if mixed with saliva in a test-tube, 

 yet they are not affected by it to the same degree in the natural 

 process of digestion. We have already mentioned the extremely 

 variable activity of the saliva, in this respect, at different times ; 

 and it must be recollected, also, that in digestion the food is not 

 retained in the cavity of the mouth, but passes at once, after mas- 

 tication, into the stomach. Several German observers, as Frerichs, 

 Jacubowitsch, Bidder and Schmidt, maintained at first that the 

 saccharine conversion of starch, after being commenced in the 

 mouth, might be, and actually was, completed in the stomach. "We 

 have convinced ourselves, however, by frequent experiments, that 

 this is not the case. If a dog, with a gastric fistula, be fed with a 

 mixture of meat and boiled starch, and portions of the fluid con- 

 tents of the stomach withdrawn afterward through the fistula, 

 the starch is easily recognizable by its reaction with iodine for ten, 

 fifteen, and twenty minutes afterward. In forty-five minutes it is 

 diminished in quantity, and in one hour has usually altogether dis- 

 appeared ; but no sugar is to be detected at any time. Sometimes 

 the starch disappears more rapidly than this ; but at no time, accord- 

 ing to our observations, is there any indication of the presence of 

 sugar in the gastric fluids. Bidder and Schmidt have also concluded, 

 from subsequent investigations, 1 that the first experiments performed 

 under their direction by Jacubowitsch were erroneous ; and it is 

 now acknowledged by them, as well as by the French observers, 

 'that sugar cannot be detected in the stomach, after the introduction 

 of starch in any form or by any method. In the ordinary process 

 of digestion, in fact, starchy matters do not remain long enough in 

 the mouth to be altered by the saliva, but pass at once into the sto- 

 mach. Here they meet with the gastric fluids, which become min- 

 gled with them, and prevent the change which would otherwise be 

 effected b} r the saliva. We have found that the gastric juice will 

 interfere, in this manner, with the action of the saliva in the test- 

 tube, as well as in the stomach. If two mixtures be made, one of 

 starch and saliva, the other of starch, saliva, and gastric juice, and 

 both kept for fifteen minutes at the temperature of 100 F., in the 

 first mixture the starch will be promptly converted into sugar, while 

 in the second no such change will take place. The above action, 



1 Op cit., p. 26. 



