The Vitamine Manual | Page 6

when the missing
tryptophan was added to the diet the animals lived a little longer but
finally declined and died. Why?
McCollum wished to answer this "Why?" These experimenters had
complied with every known law of nutrition and yet their mixtures
failed to nourish the animals. What was lacking? Earlier work at the
Station by Professor Babcock suggested an interesting line of attack
and in collaboration with Professors Hart and Humphries, McCollum
began a series of studies that have become classic contributions to the
vitamine hypothesis and brought this worker into the field as one of the
most important contributors to the subject. His initial experiments may
be briefly summarized as follows: Young heifer calves weighing 350
pounds at the start and as nearly alike in size and vigor as could be
obtained were selected as experimental animals. These were divided
into groups and fed with rations so made up as to be alike in so far as
chemical analysis could determine, but differing in that the sources of
the ration were divided between three plants. One group was supplied
with a ration obtained entirely from the wheat plant. A second group
derived their ration solely from the corn plant. A third from the oat
plant and a fourth or control group from a mixture of oat, wheat and
corn. By chemical analysis each group received enough of its particular
plant to produce exactly the same amount of protein, fat and
carbohydrate and all were allowed to eat freely of salt. All groups ate
practically the same amount of feed, and digestion tests showed that
there was no difference in the digestibility of the different rations.
Exercise was provided by allowing them the run of a yard free of all
vegetation. It was a year or more before any distinct change appeared in
the different groups. At that time the cornfed animals were in fine

condition. On the contrary, the wheat-fed group were rough coated,
gaunt in appearance and small of girth. The oat-fed group were better
off than the wheat-fed but not in so good shape as the corn-fed. In
reproduction the corn-fed animals carried their young well. They were
carried for the full term and the young after birth were well formed and
vigorous. The wheat-fed mothers gave birth to young from three to five
weeks before the end of the normal term. The young were either born
dead or died within a few hours after birth. All were much under
weight. The oat-fed mothers produced their young about two weeks
before the normal period. Of four young, so born, one was born dead,
two so weak that they died within a day or two and the fourth was only
saved by special measures. The young of the oat-fed mothers were of
nearly the same size, however, as those of the corn-fed mothers. After
the first reproduction period, the mothers were kept on this diet another
year and the following year repeated the same process with identical
results. During the first milk-producing period the average production
per day was 24.03 pounds per day for the corn-fed, 19.38 pounds for
the oat-fed, and 8.04 pounds for the wheat-fed. During the second
period it was 28.0, 30.1, and 16.1 pounds per day respectively during
the first thirty days.
Every chemical means was now employed to determine the causes of
these differences and without success. McCollum then decided to
attempt to solve the problem by selecting small animals (the rat was
used) and experiment with mixtures consisting of purified proteins
from different sources, combined with fats, carbohydrates and mineral
salts until a clue was obtained to the nature of the deficiencies. His
early results in this direction confirmed the results of other
investigators, animals lived no longer on these diets than when allowed
to fast. What was missing? Up to 1911 the main result of these
experiments had been to call attention to the peculiar deficiencies of
cereals and especially in mineral salts, but without unlocking the
mystery.
These collateral investigations show how in all parts of this country and
on the other side of the ocean events were marching toward the same
goal. The year 1911 then is a significant epoch, for from this time the

various independent efforts began to link up and the next few years
carried us far toward the goal.
In 1912 McCollum was working with a mixture consisting of 18 per
cent. purified protein in the form of milk curd or casein, 20 per cent.
lactose or milk sugar, 5 per cent. of a fat and a salt mixture made up to
imitate the salt content of milk. The remainder of that mixture was
starch. With this mixture McCollum found that growth could be
produced if the fat were butter fat but not if it were olive