furnish the body with sufficient fuel to cover its energy
expenditures. This belief was proved to be incorrect a number of years
ago by Dr. Hopkins of England. In making certain feeding experiments
with rats, Dr. Hopkins showed that some substance or substances
present in milk, other than those already mentioned, was essential for
the growth of the animal; that animals deprived of this material grew
for a time, but gradually ceased to do so. Later on, Osborne, Mendel,
McCollum and Davis discovered a like substance in butter fat; and
still later Dr. McCollum found the same growth stimulating material,
or one very like it, existing in the leaves of plants. These
scientists found, upon investigation, that there were probably two
substances in milk--one soluble in the fat, the other in the
protein-free and fat-free whey--both of which were essential for
normal growth. In 1911 Dr. Funk discovered in rice polishings a
substance which he believed to be a cure and preventive of Beri-beri;
to this substance, which is now believed to be identical with the
second substance found in milk, he gave the name "vitamine." Dr.
Funk's name "Vitamine" is now accepted to cover a number of substances
essential to growth, and for the prevention and cure of certain
diseases. To the first two has been added a third member of the
vitamine family, which has proved to be a cure and preventive of
scurvy. These substances are called--on account of the substances in
which they are soluble--"Fat soluble A," "Water soluble B," and "Water
soluble C." The table on page 496 shows the sources from which these
factors may be obtained. The four plus system is used by Dr. Eddy to
describe the abundance with which they occur.[11]

~Function of "Fat Soluble A."~--All investigators agree that the "A"
vitamine is an essential factor in the growth of young tissue, and the
repair of mature tissues. McCollum claims that this vitamine is
likewise a factor in the prevention of the eye disease known as
xerophthalmia, and other scientists also hold this opinion. Eddy
states that a diet lacking in the "A" vitamine will, in the majority
of cases, result in stunted growth and the development of the eye
disease, and that the appearance of the latter may be taken as a sure
indication of the absence or deficiency of this vitamine.

The following diagram shows the effect of adding fat soluble "A" to
the diet which was adequate in other respects. This chart represents
the gro