

FOOD-BEVERAGES. 



T N the preceding sheet, we have shewn that man 

 is destined to subsist on a mixed diet that is, 

 partly on vegetable and partly on animal food ; 

 and we shall now proceed to describe the specific 

 characters of the more common alimentary sub- 

 stances, in as far as these have been determined 

 by science and experience. In so doing, we shall 

 consider their natural history and production, their 

 chemical composition, their relative alimentary 

 value, and the like, leaving their culinary prepara- 

 tion for the subject of a separate treatise. Before 

 doing so, however, it will be necessary to establish 

 a clear conception of the functions which food has 

 to perform in the animal economy. 



The body of man, like that of all animals, is 

 composed of organic and inorganic substances : 

 the former being present as fat, albumen, &c. ; and 

 the latter as various mineral salts and water. In 

 general terms, it has been shewn by chemical 

 analysis that the human body contains in 100 

 parts : 



ic substances.... 



":;;:::::^ = 76 - 8 



IOO-0 



During life, these constituents are incessantly 

 undergoing change. Every thought of the mind, 

 every action of the body, every manifestation of 

 vitality, whatever be its nature, is accompanied 

 by an alteration of tissue ; and it is one of the 

 functions of the food to supply the tissues with 

 material wherewith to replace the losses which are 

 thus sustained. This, however, does not represent 

 the only important function of the food. For the 

 continuance of life, it is necessary that a certain 

 temperature should be maintained. While, to 

 some extent, this is done by the heat produced 

 during the chemical changes in formed tissue 

 above alluded to, those changes do not of them- 

 selves generate a sufficient amount of heat, and 

 the deficiency is made up by chemical transforma- 

 tions, resulting in the production of heat, taking 

 place in a portion of the food which has not been 

 formed into the tissues of the body. A further 

 most important function of food is the production 

 of those varieties of force or active energy which 

 manifest themselves in muscular contraction, in 

 secretion, and the like. As in the case of the 

 production of animal heat, this force is partly the 

 result of chemical changes in the formed tissues. 

 Until recently, indeed, the variety of it known as 

 muscular force was regarded, on the teaching of 

 Liebig and others, as entirely resulting from oxida- 

 tion in muscular tissue ; but extended investiga- 

 tion has now rendered it certain that muscular 

 action, in common with other forms of active 

 energy in the body, results mainly from force gen- 

 erated by the food itself, and not by the tissues. 

 No doubt, the tissues are concerned in the develop- 

 ment of force ; but in this respect their relation to 

 the food seems analogous to that of the machinery 

 in the steam-engine to its fuel, where the com- 

 47 



bustion of the fuel, and not the wear of the 

 machinery, is the cause of the generation of power. 



The substances removed from the body as 

 excrementitious or waste material are made up of 

 different quantities of inorganic and organic con- 

 stituents ; it is therefore necessary that these con- 

 stituents should be present in the food within certain 

 limits of quantity. The inorganic consist mainly 

 of water and various mineral salts, and the organic 

 of albumen a compound containing nitrogen 

 and of fat, starch, and sugar compounds destitute 

 of nitrogen; but rich in carbon. Chemistry and 

 physiology have shewn that, according to their 

 composition, these various constituents of food 

 have more or less distinct purposes to subserve in 

 the living economy. Thus, the inorganic salts build 

 up the skeleton or framework of bone ; the nitrog- 

 enous portion of the organic mainly serves in form- 

 ing or renewing the muscles and organs of the body ; 

 and the carbonaceous in supplying the energy that 

 manifests itself in heat, and muscular and other 

 forms of functional activity, and in constructing 

 fatty and other tissues. But while these general 

 statements indicate the leading purposes of the 

 different constituents of food, it must be borne in 

 mind that each of them takes a share in the main 

 purposes of all the others. For instance, the 

 organic aid the inorganic in forming bone, and the 

 nitrogenous assist the carbonaceous in generating 

 heat and muscular energy. As a matter of con- 

 venience, however, and having regard to their 

 main functions, the leading organic constituents of 

 food have been classified into the nitrogenous, or 

 plastic, or flesh-forming, and the carbonaceous, or 

 heat-producing', and the nutritive value of articles 

 of food has been estimated from the relative 

 quantities of carbon and nitrogen contained in 

 them. 



In attempting to arrive at definite conclu- 

 sions regarding the quantity and kind of food 

 required to maintain the body in a condition of 

 health, we are greatly assisted by the accurate 

 information that has been collected by many able 

 and industrious writers in connection with the 

 dietaries of troops, of large bodies of labourers, 

 and of prisoners in jails. When these dietaries 

 are contrasted with others that have proved to be 

 insufficient such as those of the Lancashire 

 operatives during the cotton famine, or of the 

 prisoners confined in Fort Sumter during the late 

 American war the minimum limit of a proper 

 dietary can be defined with very considerable 

 exactitude. Much valuable information of this 

 kind has been collected by Mulder, Liebig, Payen, 

 Christison, Playfair, Ed. Smith, and Parkes. From 

 the results of these authorities, Dr Lctheby has 

 been enabled to state the daily requirements of the 

 body in the following tabular form : 



OBll, Dltu far 



e*. 



Idleness f&J 



Ordinary Labour 4-56 



Active Labour 5-81 



I9-6A 3816 

 9-^f = 



180 

 37 



