The Vitamine Manual | Page 5

mineral salts.
Since the food furnished was composed of pure nutrients and always in
excess of the appetite of the rat the necessary number of calories was
also present. These researches were published as a bulletin (No. 156)
by the Carnegie Institution in 1911, the same year that Funk announced
his Vitamine discoveries. It was timely in this respect for one of
Osborne and Mendel's discoveries was that no matter how efficient the
mixture in all the requirements then known to the nutrition expert, the
rats failed to grow unless there was added to the diet a factor which
they found in milk. In searching for this factor they made a still further
discovery for on fractioning the milk they soon learned that the
unknown factor was distributed in two different parts of the milk,
namely in the butter fat and in the protein free and fat-free whey. The
absence of either milk fraction was sufficient to prevent growth. The
1911 publication merely described these results without attempting to
explain the nature of the growth producing factors but the vitamine
hypothesis of Funk naturally suggested to these authors that their two
unknown factors might be similar in nature to his beri-beri curative
factor and their announcement may be justly considered a point of
junction of nutrition theories with the vitamine hypothesis.
The peculiarity of butter fat as a growth stimulus had been considered
from another angle by a German worker, Stepp. In 1909 this student of
nutrition had tried to estimate the importance of various types of fats in
the same way that was later done with proteins, to determine whether,
like proteins, the quality of the fats varied in nutritive efficiency. His
experiments were also conducted with white rats and the main outlines
of his methods and observations were as follows: Rats fed on a bread
and milk diet grew normally. If now the bread and milk mixture was

extracted with alcohol-ether the residue was found to be inadequate for
growth or maintenance. Stepp assumed that this failure could naturally
be ascribed to the removal of the fat by the alcohol-ether mixture. To
determine the efficiency of different kinds of fats he then proceeded to
substitute in combination with the alcohol-ether extracted diet amounts
of purified fats corresponding to what was removed by the
alcohol-ether. The results were totally unexpected for none of the
purified fats substituted were adequate to secure growth! When,
however, he evaporated off his alcohol- ether from the extract of the
bread and milk and returned that residue to the diet, growth was
resumed as before. The conclusion was obvious, viz., that alcohol-ether
takes out of a mixture of bread and milk some factor that is necessary
to growth and that factor is not fat but something removed by the
extraction with the fat. These results led Stepp to suspect the existence
of an unidentified factor but he was unable to identify it as a lipoid. He
makes the following statement which is now significant: "It is not
impossible that the unknown substance indispensable to life goes into
solution in the fats and that the latter thereby become what may be
termed carriers for these substances." These studies were published
between the years 1909 and 1912 and were therefore concurrent with
those of Funk and Osborne and Mendel.
But there was still another set of studies that led up to this vitamine
work. In 1907 E. V. McCollum began the study of nutrition problems
at the Wisconsin Experiment Station. At the time he was especially
interested in two papers that had been published just previous to his
entrance into the problem. One of these papers by Henriques and
Hansen told how the authors had attempted to nourish animals whose
growth was already complete on a mixture consisting of purified
gliadin (the principal protein from the quantity viewpoint in wheat),
carbohydrates, fats, and mineral salts. In spite of the fact that the
nitrogen of this mixture was sufficient to supply the body needs, as
proved by analysis of the excreta, the animals steadily declined in
weight from the time they were confined to this diet. The authors had
assumed that the gliadin was deficient in a substance necessary to
growth (lysine) but since their studies were begun only after the
animals had reached maximum growth they expected that the growth

factor would not be necessary. Why had their animals declined in
weight?
The second paper that interested McCollum was by Wilcock and
Hopkins. These authors carried out experiments similar to those of the
paper just cited but using corn protein (zein) in place of gliadin. This
protein had already been shown to be deficient in a chemical
constituent known as tryptophan. Animals fed on the zein mixture died
in a few days but the inexplicable thing was that