32 SALIVA. 



exerts no action on starch, sugar may be detected by the ordinary 

 means in the stomach of the animal in 10 or 15 minutes after it 

 has swallowed balls of starch, or after they have been introduced 

 through the fistula. Hence it cannot be doubted that the saliva, 

 after it has been mixed with the other animal secretions, con- 

 tinues to exert its action on the amylacea in the digestive canal. 



Notwithstanding the evidence which has been adduced to prove 

 that the saliva exerts this action on starch, there are other facts 

 which seem to show that we must not assign to it an extreme 

 importance in the digestive process in general. For, even if we 

 do not admit the conclusiveness of Budge's* experiment, in which 

 he extirpated all the salivary glands of a rabbit, and afterwards 

 observed no disturbance of the digestive system, and no imperfec- 

 tion in the nutrition, yet on the following grounds we must regard 

 this action of the saliva as a somewhat limited one : the quantity 

 of the saliva which is secreted is altogether independent of the 

 quantity of starch contained in the food, and is extremely small 

 when the latter is taken in a fluid form; when food which has 

 been thoroughly moistened is swallowed, there is only a very 

 slight secretion of saliva ; liquid and moistened foods remain in 

 the stomach so short a time, that a perfect conversion of the 

 starch into sugar in this organ is impossible ; nature has, however, 

 provided a secretion which is poured into the duodenum the 

 pancreatic juice, which possesses the power of effecting this con- 

 version of starch into sugar in a far higher degiee than the saliva; 

 animals (fishes, for instance) which swallow amylaceous food 

 without masticating it, possess for the most part such rudimentary 

 salivary glands, that the secretion from them can hardly be taken 

 into consideration. But even the pancreatic juice is not generally 

 sufficient to effect the perfect metamorphosis of the starch ; the 

 conversion proceeds so slowly that we can almost always detect a 

 considerable quantity of starch in the excrements not only of 

 carnivorous but also of herbivorous animals, after the ingestion 

 of amylaceous food. Hence it appears very much to depend on 

 the subjective opinions of different writers, whether a greater or 

 lesser importance in this point of view be attributed to the saliva ; 

 in no case, however, should the function of the saliva as a sacchari- 

 fying agent be overrated. 



This is a subject on which special observations, experiments, 

 and criticism, are peculiarly needed ; and it is by the neglect of 

 this mode of inquiry that some of the best observers have been 

 * Rhein. Blatt. Bd. 4, S. 15. 



