416 NUTRITION. 



to the chemical phenomena of nutrition, the facts and the con- 

 clusions to be deduced from them, which have hitherto been 

 obtained from statistical investigations. 



The next question which must engage our attention in this 

 respect, is to determine the amount of food which, under normal 

 relations, is daily subjected to the metamorphosis of matter in an 

 adult man, and the mode in which the products, into which the 

 nutrient matters are decomposed during their stay in the body, are 

 distributed in the excretions. The earliest exact investigations of 

 this kind were made by Valentin* on his own person. His bodily 

 weight being 53 kilogrammes, Valentin found that he consumed in 

 the twenty-four hours on an average 2924*03 grammes of mixed 

 food ; of the products of metamorphosis which were excreted 

 during that time 190*73 grammes were eliminated with the solid 

 excrements, 2447*70 grammes with the urine, and 1246*93 grammes 

 with the perspiration; the ratio of the solid and fluid to the 

 gaseous excretions is, therefore, on an average as 1 : 0*833. This 

 estimate seems tolerably high for the perspiration ; but it appears 

 from Valentin's special investigations, that the main factor which 

 raises the amount eliminated by the perspiration is especially the 

 separation of water through the skin, on which account this propor- 

 tion must be totally different in animals. 



The experiments of Rawitz,f which were conducted with great 

 patience and self-sacrifice, still leave much to be desired in 

 reference to their exactness ; the mean of twenty-two observations, 

 in which he studied the effect of many of the most common 

 articles of food, yielded on an average, fora consumption of 1875*4 

 grammes of mixed food, 1 136 '4 grammes of egesta through the 

 intestine and kidneys, and 739*0 through the perspiration ; the ratio 

 given by Rawitz of the solid and fluid to the gaseous egesta differs, 

 therefore, very considerably from that of Valentin, being as 

 1 : 0*650 ; the ratio in his individual observations was extremely 

 fluctuating, as was also the case with Valentin. 



Rigg t determined the ingesta and egesta of a strong man, in 

 accordance with their elementary constituents ; he obtained results 

 which accorded tolerably well with those of other observers : it is 

 however remarkable, that for 100 parts of the nitrogen which was 



* Valentin's Report. 8. Jahrg ; Handworterbuch der Physiologie. Bd. 1, 

 S. 367-470 ; and. Physiol. d. Menschen. Bd. 1, S. 710-780. 

 t Ueber die einfachen Nahrungsmittel. Berlin, 1842. 

 J Medical Times, 1842, p. 278. 



