COLOMBO. 
Added as a Sxipplcment Monthly to the "TROPICAL AGIUCULTUBIST:' 
The following pages include ihe Contents of the AgricuUuml Magazine for 
_April : — 
Vol. XIV.] 
APEIL, 1903. 
[No. 10. 
TEINCIPLES OF NUTRITION AND NUTEITIVE 
VALUE OP FOOD, 
HIS is the subject of a learred- 
pttjjer by Prof. W. O. Atwater, 
of tlie United States Department 
of Agriculture, who as special 
agent in charge of nutrition 
investigatious, speaks witli au' 
tliority on this very important subject. 
There is so much in it that should come within 
the knowledge of both grower and consumer, 
that we have decided to summarise the contents 
of the pnper for the benefit of our readers who 
vpill no doubt be able to leiirn a great deal about 
the true value — nutritive aud pecuniary — of food, 
as well as the general subject of diet, the errors 
of which has so much to do with the welfare 
of mankind. 
It is well known that the chemical substances 
of which the body is compared are made 
up of the same element as those of the foods 
which nourish it. The most abundant of the 15 
or 20 elements occurring in the human body 
are oxygen, hydrogen, carbon, nitrogen, calcium, 
phosphorus and sulphur, which combine to form 
a variety of compounds. The most important 
among these latter are the substances distin- 
guished as protein, fats, carbohydrates, 
mineial matter and water, whose functions stated 
generally are to build and repair the various 
tissues of th« body, and to supply it with heat 
and muscular energy. 
Water is among the most important compounds, 
forming over 60 per cent of the weight of the 
body of the avernge man, being itself a 
component of all the tissues. 
Mineral matter or ash forms 5 or 6 per cent 
of the body weight, and is found chiefly in 
the bones and teeth, though also present in 
the tissues and fluids, Phosphote of lime is the 
mineral basis of bone, and compounds of potas- 
sium, sodium, magnesium and iron are found 
in the body and are necessary to life. 
Protein includes the principal nitrogenous 
compounds and it familiar in the form of meat' 
white of egg, &c. It forms 18 per cent of the 
body weight in the average man. The albumin- 
oid proteids include substances similar to 
white of eggs, lean of meat, curd of milk, &c. 
The gektinoids occitr principally in the connective 
tissue?, and with the albuminoids are the most 
important constituents of our food, forming the 
basis of bone, muscle and other tissues. They 
yield heat on combustion, and are to some extent 
transformed into fat and stored in the body. Pro- 
teids are most abundant in the animal foods though 
also present in cereals, and, in large proportion, 
in legumes. It should be added that the gela- 
tinoids are less valuable than the albuminoids for 
nutriment. The "extractives" though classed as 
proteids are very different from the two already 
mentioned. They are the c-tief ingredients in 
meat extracts, such as beef ten, &c. They are 
believed neither to build up tissue nor supply 
energy, but act as stimulants and-appetisers. The 
nitrogenous compounds of vegetables contain 
more or less of the so-called nmids analogous 
to the extractives of meat. Fats occur chiefly . 
in animal foods, but are nlso found as oily 
matter in seed.^. When the food supply is shnrt, 
fat, and also proteii", is drawn upon to supply 
heat. Fat forms 1.5 per cent of the avevnpe 
body weight. The tendency to fatness is net 
