70 PHYSIOLOGY AT THE FARM. 



the parotid nor the subm axillary saliva exerts any action on 

 starch, the common or the mixed saliva of the horse converts 

 both crude and boiled starch into sugar at the temperature 

 of the animal body. And it is now acknowledged by most 

 physiologists that the pancreatic juice possesses this power of 

 transmuting starch into sugar in a far higher degree than the 

 mixed saliva. It seems established that the gastric juice exerts 

 no such effect on starch ; and authorities are still divided 

 on the question whether the intestinal juice below the duo- 

 denum possesses the property of changing starch into sugar. 

 This change of starch into sugar is believed to take place by 

 the influence of an azotised ferment contained in the fluids 

 just referred to, by which the starch is converted first into 

 dextrine (the substance so long known as British gum) and 

 then into sugar. Thus, as respects starch, digestion goes on 

 in the following manner: As the food remains but a short 

 time in the mouth, little more can be accomplished there 

 beyond the free admixture of the mixed saliva with the mass 

 of food, whence the greater part of the starch passes unchanged 

 into the stomach. In so far as the gastric juice is applied to 

 the mass of aliment, the process of the conversion of starch is 

 suspended that is, this process is postponed at the outer sur- 

 face of the mass which is immediately acted on by the gastric 

 juice; but in the interior parts of the mass, to which the gastric 

 juice does not at once gain access, the starchy parts thereof 

 for a time are left to the undisturbed operation of the saliva 

 imbibed by it in the mouth. Doubtless, however, much of the 

 starch escapes this change in the stomach, as the process is 

 suspended as soon as the gastric juice gains access to its 

 particles. But after the due sojourn in the stomach, what 

 remains of the starch comes into the duodendum, and is there 

 brought into contact with the powerfully acting pancreatic 

 juice, when the metamorphosis commences anew. In the ilium 



