METABOLISM. 
By E. A. Schafer. 
Contents : — Introductory, p. 868 — Balance of Nutrition, \i. 871 — Composition of 
Foodstuffs, p. 872 — Heat Value of Foodstuffs, p. 874 — Necessary Amount of 
Proteid, p. 875 — Special Constituents of Diet, and their Effect on Metabolism, 
p. 878 — Gelatin, p. 878 — Carbohydrates, p. 880 — Fats, p. 881 — Inorganic Sub- 
stances, p. 882 — Metabolism in Inanition, p. 887 — With purely Proteid Diet, 
p. 891 — Relative Metabolic Activity of Tissues, p. 895 — Nitrogenous Meta- 
bolism, p. 896 — Influence of the Liver on Proteid Metabolism, p. 900— Influence 
of Muscular Activity on Proteid Metabolism, p. 911 — Metabolism of Carbo- 
hydrates, p. 916 — Glycogen formation, p. 919 — Phloridzin Diabetes, p. 920 — ■ 
Glycogenesis, p. 922 — Puncture Diabetes, p. 926 — Action of Pancreas on 
Carbohydrate Metabolism, p. 927 — Metabolism of Fat, p. 930 — Source and 
Formation of Fat, p. 931 — Action of Liver on Metabolism of Fat, p. 935. 
Introductory. — The word " metabolism " has come into use in this 
country as the equivalent of the German word Stoffwechsel, which 
strictly means " exchange of material." The subject which it denotes 
embraces all that is known or conjectured regarding the changes which 
occur within the body in the materials of the food, or foodstuffs, and 
in the materials which compose the tissues and organs of the body 
itself, or bodystuffs. Generally, however, the digestive changes in the 
food are excluded from the scope of the expression. There is no special 
reason, other than that of convenience of description, why this should be 
the case, for the digestive changes in the food must, like all other 
chemical changes occurring within the body, influence the general con- 
ditions of the economy. The usual course will, however, be followed 
in this article, and I shall confine what I have to say to the changes that 
occur after the food is absorbed, in so far as they have not been already 
treated of in the articles in this work dealing with the chemistry of the 
urine and with the chemical processes of respiration and heat production, 
both of which subjects constitute essential parts of the whole subject 
of metabolism. 
The metabolic changes which are undergone by the tissues must be 
of two kinds, which are opposite in nature. 1 For, on the one hand, the 
complex molecules which constitute living tissue or biojilasm, 2 are built 
1 Hering, " Vorgange der lebenden Materie," Prag, 1888. A translation, by Miss F. A. 
Welby, of this extremely important and interesting article will be found in Brain, London, 
1897, vol. xx. p. 232. 
2 I use the word bioplasm as a synonym for living substance, rather than protoplasm, 
because the latter word has come to have a definite histological rather than a physiological 
signification ; and, on the one hand, is used to include portions of cell substance which, for 
aught we know, may not be actually living matter, whilst, on the other hand, it does not 
include the living substance of the cell nucleus, which would be included in the expression 
" bioplasm." 
