Supflemeni to the Tropkal Agnevlturist." [April 1, 190S, 
decided by food and exercise alone, but depends 
also on personal idiosyncracy or some other little 
understood factor. Sugar and starch of foods are 
charged into and stored as fat in the body. 
Carbohydrates. — These include starches, sugars 
and cellulose -which occur chiefly in vegetable 
■foods, though, milk contains much sugar. The 
carbohdyrates form less than 1 per cent of the 
body. Starches and sugars are important as being 
a source of energy, and are easily digested. 
In discussing the nutritive value of food we 
must discard the refuse part of it, such as bones 
of meat, shells of eggs, skin and seeds of fruit, in 
order to find the actual cost of the nutrients. • 
The potential energy of food is transformed in 
the body into heat and mechanical power. The 
latter is required for work, the former is. used to 
keep the body warm, and when more is generated 
than is needed for that purpose it is wasted. The 
body is indeed a mnchine, but unlike other 
machine it is self -building, self-reparing and 
gelf-regulating. It is, however, more than a 
machine in that it has a nervous organisation, 
sansibilities, and the higher intelltctual and 
spiritual facilities, the right exercise of which 
undoubtedly depends upon the right nuritiou of 
the body. 
Shortly stated the uses of food are (1) to form 
th« material of the body and supply its waste, 
(2) to yield heat for the warmth of the body 
and furnish muscular and other power for its 
work. The principal tissue formers ar« the 
proteids, sspecially the albuminoids which moke 
the frame-work of the body, build up and repair 
nitrogenous materials (muscles, tendons) and 
supply the albuminoids of tlie blood and other 
fluids. The albuminoids of food are transformed 
int(X albuminoids and gelalinoids of the body. 
Musc'e, tendon, cartilage, bone, skin, blood cor- 
puscles, the casein of milk are all made from them. 
The gelatinoids of food, such as the finer pnrliclees 
of tendon and the gelatin (which are difsolved 
out of bone and meat in soup) though not 
believed to be tissue formers, protect the albu- 
minoids from consumption, When the food con- 
tains gelatinoids in abundance, less of the albu- 
minoids is used. The proteids can be so changed 
in the body as to yield futs and carbohydrates, 
and are also burned directly in the body like 
carbohydrates. The material of lean meat may be 
converted into muscle and its energy into heat and 
muscular power, but a one-sided diet of meal is 
unsuitable. Futs and carbohydrates (starch, 
sugar) are the chief fuel ingredients of food — ths 
former being the more concentrated fuel. The 
fat stored in the body for food, and that formed 
in the body from carbohydrates, act as reserve 
6Ui)plies of fuel. While the functions of the 
different nutrients are inteichangable, only albu- 
minoids Clin do the work of building and repair. 
Heat and muscular power are forms of force or 
energy. The energy latent in food is developed 
as the food is consumed. When combustible 
matter is oxidised, be it meat or wood, bread or 
coul, the Intent energy becomes active and is 
tninsformed in(o heat and pov\er. Again, as 
various kinds of fuel differ in the amount of heat 
they produce, fco various kinds of food give off 
different amounts of energy, and hence have 
different values as heat-producing substances. 
When a man does no muscular work (beyond 
respiration, circulation, &c.) all the energy leaves 
the body as heat ; otherwise it is expended partly 
in this way and partly in muscular work. Any 
waj', the interesting point is that the energy 
given off is exactly equal to the latent energy of 
the material burned in 1;he body. The body thus 
obeys the great law of the conservation of energy 
_ which obtains in the j hysical world. In practi- 
cally applying the piinciple of this law to the 
body, we have to take into account the chemical 
composition of food, the proportion of nutrients 
actually digested and oxidised, and the proportion 
of the whole latent energy of each which becomes 
active and useful for warmth and work. Taking 
our common food materials as they are used in 
ordinary diet, the following is a general estimate 
for the energy furnished by 1 lb. of each class of 
nutrients : — 
Protein fuel value, 1,820 caloriei per lb. 
Fats „ 4,040 „ „ 
Carbohydrates „ 1,820 „ „ 
" [One calorie is equal to very nearly 1*54 foot 
tons, that is to say, one calorie of heat, when 
trans formed into machanical power, would suffice 
to lift 1 ton 1 54 feet.] 
It will thus be seen that a pound of protein of 
lean meat or albumen of egg is about equivalent 
to one of starch or sugar as regards fuel value, 
and that a little over 2 lbs- of either would be 
equal to a pound of meat or butter fat. 
Thus the fuel value depends upon the amounts 
of the nutrients, especially fat. 
Here are a few instances of the fuel value of 
common foods themselves: — 
Wheat flour ... 1,625 calories per lb. 
Butter ... 3,410 „ „ 
Milk ... 310 „ „ 
Cream ... 865 „ „ 
Skin milk ... 165 „ „ 
(To be continued.) 
OCCASIONAL KOTES. 
The flowering tree now pretty common about 
Colombo and popularly known as " Madre de 
Cacao" has at last been fully nnmeA Millettia 
atropurpurea by Sir Joseph Hooker. The seeds 
originally cnme to the late School of Agriculture 
frona Central America in exchange for seeds of 
the Dhall or pigeon iiea (Cajanus indicus). The 
tree is very easily grown from cutting?, and is 
rapidly spreading as a shade and hedge plant, 
while the blossoms, which apj ear in February- 
March, are really handsome. 
The curious name " Arthapal " by which the 
English potato {k'olanum tuberosum) is locally 
known is only a corruption of "earth apple" 
(pome de terrc) not to be confounded with earth 
nut or ground nut {Arachis hypogaa). "Potato" 
is said to bedeiived from "batata"' (the Spanish 
for sw eet potato) which must therefore have been 
known before the former. By-the-bye has any one 
heard the term " ratu-imiala " applied to the 
