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The amounts of fat in the vegetable foods are so small 

 that the experiments do not tell exactly what proportions are 

 digested. The meats and fish contain practically no carbo- 

 hydrates. The digestibility of the carbohydrates (sugar) of 

 milk was not determined, those of the vegetable foods except 

 the beets, were almost completely digested. That the protein 

 of cow's milk should be so much less completely digested 

 than that of meal seems a little strange. Children have been 

 found to digest a little more than adults, though the difference 

 is not large. Thus Dr. Camerer, a German experimenter, 

 found his boys and girls of from two to twelve years of age to 

 digest from ninety-one to ninety-seven per cent, of the protein 

 of cow's milk, while grown men in experiments by Dr. Rubner 

 digested from eighty-eight to ninety-four per cent. But in 

 experiments in which milk and cheese were eaten together by 

 a man, the laboratory servant of Dr. Rubner's experiments, 

 all or nearly all of the protein of both was digested. The 

 percentages of fats of milk digested was practically the same 

 with adults as with children. It is worth noting in these 

 experiments, both children and adults digest only about half 

 of the mineral salts of the milk. Why so much of the fats of 

 the meat, from a twelfth to a fifth, should have failed to be 

 digested it is not easy to say. Some of the food materials, as 

 meat, bread and milk, have been tested each by several 

 experiments with more than one person. With others, as 

 €ggs, corn meal, rice, pease and potatoes, only a single trial has 

 been made. Doubtless extended series of tests would give 

 averages differing more or less from these figures. Another 

 thing that makes the results a little uncertain, is that some of 

 the food materials may perhaps be more completely digested 

 Avhen taken in small quantities with others in the ordinary 

 way than when so much of them is eaten and without any 

 other food. These and other sources of slight error make 

 more extended experiments very desirable. But enough has 

 been done to show pretty clearly that : 



1 . The protein of our ordinary meats and fish is very readily 

 and completely digestible. 



2. The protein of vegetable foods is much less digestible 



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