THE NECESSITY FOR A MIXED FOOD. 413 



substances passes into the intestinal excrements, for although we 

 have learnt that far less bile passes into the excrements than was 

 formerly supposed to be the case, we have seen that the intestinal 

 excretion is by no means inconsiderable for certain substances. A 

 far smaller quantity of bile and intestinal mucus is, however, 

 secreted in a fasting state than in a condition of repletion. Yet 

 notwithstanding these uncertainties. Boussingault's results retain 

 their value, for if we were not possessed of these direct determina- 

 tions, we should scarcely be able to obtain even an approximately 

 correct idea of these relations. We have, therefore, simply given 

 in the following table the results obtained by Boussingault's inves- 

 tigations, according to which the different substances pass in one 

 hour, in the quantities indicated, from the intestinal canal into the 

 blood of a duck. 



Grammes. Grammes. Grammes. 



Dry rice (8'68g of albumen and 89'2 of starch) = 4'20 (= 0'34 of albumen and 3'86 of starch). 



In connection with these uncertain determinations, several 

 highly interesting considerations here suggest themselves, to which 

 we shall revert at a future page ; contenting ourselves for the pre- 

 sent with the observation, that the albuminous substances alone 

 are totally insufficient for the restoration to the body of the carbon 

 which is lost by respiration ; according to Boussingault, a duck 

 expires in one hour 1*25 grammes of carbon, whilst the albuminates 

 which are resorbed within an hour contain at most only 1*0 gramme 

 of carbon. Fats or carbo-hydrates must, therefore, necessarily be 

 commingled with the albuminates, in order that there may be a 

 due compensation in the body for the loss of carbon which normally 

 occurs through the respiration. It is still more striking, that the 

 quantity of fat which is resorbed in one hour should be wholly 

 inadequate for this restitution of the carbon ; 0*84 of a gramme of 

 fat, which is all that is resorbed during one hour, contains about 0*7 

 of a gramme of carbon, and, therefore, scarcely half as much as is 

 exhaled by the lungs in one hour. The carbo-hydrates are, how- 



