ON THE BALANCE OF THE VITAL ECONOMY. 



421 



their usual obstinate persistence, occasionally disappear. The normal type 

 is, perhaps, less likely to be thus recovered, when the departure from it is 

 very slight, and consists rather in the wrong plan (so to speak) on which the 

 new matter is laid down, than in a perversion of the nutritive process itself. 

 It may be useful to conclude this section with a table showing the proportion 

 which the several component parts of the body bear to one another. 1 It will 

 be seen how large a percentage of the body is composed of the soft tissues, in 

 which rapid processes of disintegration and reconstruction are constantly in 

 course of performance : 



The proportion of water in the body of adults is about 58.5 per cent. ; in the new- 

 born child, 66.4 per cent.; the muscles contain 75.7 per cent ; the fat, 29.9; the 

 skin, 72 ; the blood, 83 ; the liver, 69.3 ; and the brain, 75 per cent, of that fluid. 



2. On the Balance of the Vital Economy, or the Relations which subsist between 

 the Ingesta, the Metamorphosis of Tissue, the Work accomplished in and 

 by the Body, and the Ingesta. 2 



337. During the last few years many laborious investigations have been 

 undertaken, with a view to determine what may be called the " balance of 

 the vital economy ;" or in other words, to ascertain not only the kind and 

 quality of food requisite to maintain life under varying external conditions, 

 but to gain an insight into the manner in which different kinds of foods are 

 applied to the formation of tissue, the production of mechanical force, and 

 to the maintenance of animal heat; and also the mode in which the results 

 of their metamorphosis within the body are ultimately discharged by the 

 various excretory organs. The average amount of food required by the 



1 From Eanke, Grundziige der Physiologic, _1868, p. 143. 



2 The following are some of the more important recent works on this subject: 

 Bidder and Schmidt, Die Verdauungssafte und der Stoffwechsel, 1852. Lawes and 

 Gilbert, Philosoph. Trans., 1859. Bischoff and Voit, Die Gesetze der Ernahrung 

 des Fleischfressers, Leipzig, 1860. Henneberg and Stohmann, Beitriige zur Hat. 

 Futterung der Wiederkauer, Braunschweig, 1860. Ranke, Archiv f. Anat. und Phys., 

 1862. Pettenkofer and Voit, Annal. d. Chemie und Pharmacie, 1862. Sehtttzen- 

 berger, Chimie applique a la Physiologic. Seegen, Sitz.-ber. d. Wien. Akad., Bd. 

 Iv, Ixiii, 1871. Voit in Zeits f. Biologie, Bd. ii, 1866, pp. 6 and 189, Bd. iii, 1867, 

 p. 1, Bd. iv, p. 517 (uber Luxus Consumption), and his experiments either alone or 

 in conjunction with Pettenkofer in the succeeding six volumes of this periodical, 

 which contains numerous other articles on this subject by different workers. The 

 Editor must here acknowledge his obligations to the standard works of Funke, Lud- 

 wig, Vierordt, Budge, Longet, Milne-Edwards, Wundt, Herrmann, and Kankc ; in 

 each of which, excellent sections on Nutrition will be found. 



