590 



METABOLISM, NUTRITION AND DIETETICS 



SECTION IV. STATISTICS OF NUTRITION THE INCOME AND 

 EXPENDITURE OF THE BODY IN TERMS OF MATTER.* 



Preliminary Data. The office of the food is to maintain the con- 

 stituents of the body upon the whole in their normal proportions. A 

 knowledge of the chemical composition of the body is, therefore, an 

 important datum in the consideration of the statistics of its metabolism. 

 The body of a man analyzed by Volkmann had the following composition : 



Inorganic substances - 



Organic substances 



Water - - 65-9 per cent. 



Mineral matter - - 4*4 > 

 'Carbon 18-4 per cent."j 

 Hydrogen 2-7 ,, I 

 Nitrogen 2-6 ,, f 2 

 .Oxygen 6-0 ,, J 



The muscles, the adipose tissue, and the skeleton form nearly four- 

 fifths of the total body-weight in the adult. The following table shows 

 the percentage amount of each of these tissues in a man, a woman, and 

 a child (Bischoff) : 



The nitrogen is contained chiefly in the muscles, glands, and nervous 

 system, and in the constituents of the connective tissues, which yield 

 gelatin, various mucoids, and elastin. The ordinary proteins make up 

 about 9 per cent, of the weight of the body, or 22 per cent, of its solids; 

 the albuminoids or sclero-proteins (gelatin-yielding material, etc.) (p. 2) 

 about 6 per cent, of the body-weight. Nitrogen exists in proteins to 

 the extent of 16 per cent., so that the 6-5 kilos of protein of a yo-kilo 

 body contain about i kilo of nitrogen. 



The carbon is contained chiefly in the fat, which forms a very large 

 proportion of the water-free substance of the body, and in the proteins. 

 A small amount is present as calcium carbonate in the bones. In the 

 body of a strong young man weighing 68-6 kilos, Voit found the following 

 quantities of dry fat in the various tissues : 



Adipose tissue 



Skeleton 



Muscles 



Brain and spinal cord 



Other organs 



Total - 



8809-4 grammes. 

 2617-2 ,, 



636-8 



226-9 

 73*2 



- 12363-5 



equivalent to 18 per cent, of the whole body-weight, or 44 per cent, of 

 the solids. In dry fat rather more than 75 per cent, of carbon is present, 

 and in protein about 50 to 55 per cent. ; so that while the fat of the body 

 analyzed by Voit contained more than 9 kilos of carbon, only about a 

 third of this amount would be found in the proteins. 



* The income and expenditure of the body in terms of energy are considered 

 in Chapter XII. 



