BALANCE OF NUTRITION. 871 
have been dealt with in previous articles. So far as the bodystuffs are con- 
cerned (and to a somewhat less extent with regard to the i Istuffs), it cannot 
be said that we possess an acquaintance so intimate as to enable us fully to 
understand the changes which they undergo j and as a consequence it will be 
found that our knowledge of metabolism, in spite of the enormous amount of 
work that has been dune to elucidate it within the last five and twenty years, 
is still in an unsatisfactory condition. 
Balance of nutrition.— The first determinations that require to be 
made in any inquiry into the metabolism of the body are those of its 
incomings and outgoings. 1 The incomings of the body consist of food 
and oxygen : the outgoings, of the various excreta, and of the carbon 
dioxide and water lost by the lungs and skin. If the incomings of the 
body exactly balance the outgoings, so that the animal neither gains nor 
loses weight, the body is said to be in comjiI<f, nut rifle t <jnl/lJ>i-lum. 
Sufficient information can Vie usually obtained regarding the balance 
of metabolism of the body, if the nitrogen and carbon only are determined 
in the ingesta and egesta. 
As an instance of complete equilibrium in a man weighing 70 kilos., 
embracing both the nitrogen and carbon of the ingesta and egesta, the 
following balance table may be given (Burdon Sanderson 2 ) : — 
Incomings. 
Outgoings. 
Food. 
X. 
0. 
Excreta. 
X. 
C. 
Proteids . lOOgrms. 
Fat . . 100 ,, 
Carbohydrates 250 ,, 
1 .*>■.", 
53 
79 
93 
Urine 
Faeces 
Respiration 
14'4 
1-1 
6-16 
10-84 
208-00 
15'5 
225 
15'5 
| 225 
We may also have a condition in which the body either gains or 
loses weight, and in which consequently the incomings and outgoings do 
not exactly balance one another, but during which, nevertheless, the 
nitrogen which is taken into the body, and that which leaves the body, 
may strike an exact balance, while the other elements which compose 
the food and excreta, and especially the carbon, hydrogen, and oxygen, 
may not be similarly balanced. When the nitrogen of the food exactly 
balances the nitrogen excreted, the body is said to be in nitrogenous 
equilibrium. Under these circumstances we may assume that the living 
material of the tissues (which is essentially composed of nitrogenous 
substance) is neither diminished nor increased in amount : whereas, if 
at the same time the other constant elements of the food — the carbon, 
hydrogen, and oxygen — are met with in diminished or increased quantity 
in the excreta, we may assume that substances in the body other than 
the living tissues are either becoming laid on, or becoming diminished 
1 For the methods of determining these may be consulted, C. A'oitin Hermann's '-'Hand- 
buch," 1881, Bd. vi. S. 6 et seq., and numerous papers which have appeared since then 
chiefly in the Arch. f. d. ges. Physiol., Bonn (by Pfluger, Zuntz, and their pupils), and in 
the Ztschr. f. Bio!., Munchen (by Voit and his pupils). See also v. Xoorden, "Grundiiss 
einer Methodik der Stoffwechsel-Untersuchungen," Beidin, 1892. For the methods of deter- 
mining the respiratory products, see article '"Chemistry of Respiration 1 '). 
2 " Syllabus of Lectures on Physiology," 1879. 
