DIGESTIBILITY OF FOOD. 321 



in the small intestine, and, to a certain degree, also in the large 

 intestine; for even if, in accordance with the observations of 

 Bidder and Schmidt, we regard the secretion of the intestinal 

 juice in the latter as inconsiderable, the enormous size of the 

 csecum in most of the herbivorous animals indicates that a very 

 essential act in the process of digestion must take place in this 

 region. The chief difficulty in connexion with the digestion of 

 vegetables, therefore, does not lie in the stomach, and hence their 

 retention in that organ cannot be strictly considered as a measure 

 of their digestibility; and yet vegetables remain on an average 

 longer in the stomach than animal food. Even after feeding an 

 animal with bread, we may find the greater part of it in the 

 stomach after a lapse of 3 hours, and the quantity hardly per- 

 ceptibly diminishes till after 4 hours (Frerichs), and remains of 

 bread are commonly found in the stomachs of dogs after 5 or 6 

 hours, and often even after 8 or 10 hours: potatoes and other 

 vegetables remain in this organ for a far longer time ; Frerichs, as 

 well as Bidder and Schmidt, have frequently found the remains of 

 vegetable substances in the stomachs of dogs after the lapse of 22 

 hours ; and we have already mentioned that the stomach in many 

 herbivorous animals is never completely empty. If we have thus 

 established the point that the disappearance of an article of food 

 from the stomach affords no proof of its digestibility, the next 

 question that suggests itself is in relation to the conditions under 

 which the stomach either retains or impels into the small intestine 

 the more or less digested matters a question to which, in the 

 present state of our knowledge, we can give no satisfactory 

 answer. This is one of the least important of the many problems 

 whose solution must be left to future investigators, notwith- 

 standing the admirable and comprehensive labours of Frerichs and 

 of Bidder and Schmidt. We are, however, here forcibly reminded 

 of the fact, that notwithstanding the brilliant triumphs of science 

 in this direction, we have as yet only gained the outworks from 

 which further advances must be made. 



As we have limited ourselves in the former pages almost 

 exclusively to the consideration of the principles which, in accord- 

 ance with the present condition of science, ought to guide us in 

 our judgment of the digestibility of the different articles of food, 

 some of our readers may miss the important aids and special 

 indications they may here have hoped to discover in relation to 

 medical practice ; for many physicians seem to entertain the idea 

 that physiological chemistry must be able to decide all questions 



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