rhaps partly on
account of the fact that marching is often monotonous and the scenery
uninspiring. Still, even after a good evening hoosh, the subconscious
self may assert itself in food-dreams. The reaction from even a short
sledging trip, where food has been plentiful, is to eat a good deal,
astonishing in amount to those who for the time being have lived at the
Hut.

It may appear that a serious case is being made against the polar
sledging ration. On the whole, it was found to be excellent and the best
that experience had been able to devise. Entering the polar zones, one
must not be over-fastidious, but take it as a matter of course that
there will be self-denial and deprivation of small luxuries.

The energy exerted by man, and the requirements of tissue-building
are derived from the organic compounds known as proteins,** fats and
carbohydrates, though in a slight degree from other substances, most
important of which are minute quantities of mineral matter.

A calorie as used in dietetics is the amount of heat required to raise
the temperature of one kilogramme of water at 0 degrees C. to 1 degree
C. The heat-value of food-stuffs, stated in calories, can be quickly
reckoned when chemical analyses stating their protein, fat and
carbohydrate contents are available. It has been ascertained that one
gramme of protein or carbohydrate yields 4.1 calories, whilst the same
amount of fat produces 9.3 calories. Thus the value of fat-containing
foods in a sledging ration is at once apparent.

** The proteins are complex nitrogenous compounds which are preeminent
in fulfilling the two functions of a food: to form tissue and to produce
work and heat. As examples may be quoted, myosin the chief protein of
ordinary meat or muscle, ovalbumin one of the proteins of egg-white,
casein belonging to milk and cheese, and gluten a protein-mixture in
flour.

Fats are organic non-nitrogenous substances obtained from both animal
and vegetable sources, e.g. butter and olive oil.

The carbohydrates are compounds of carbon with hydrogen and oxygen in a
certain proportion, e.g. cane-sugar and starch.

Mineral matters are inorganic, being chlorides, carbonates or phosphates
of calcium, sodium and potassium.

Theoretically, any of the three classes of foods mentioned might be
thought to supply adequate energy, if taken in sufficient amount.
Practically, however, protein and carbohydrate are essential, and it is
better to have