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The Vitamine Manual by Walter H. Eddy
page 34 of 168 (20%)
It will be evident that in the absence of exact tests for a substance
which is unknown chemically the problem of detecting its presence must be
a matter of indirect evidence. When a chemist is presented with a solution
and asked to determine the presence or absence of lead in that solution he
knows what he is seeking, what its properties are and how to proceed to
not only determine its presence but to measure exactly the amount present.
No such possibility is present in a test for vitamines, but this lack of
knowledge as to the vitamine structure has not left us helpless. We do
know enough of its action to permit us to detect its presence and the
technique that has been developed for this purpose is now well
standardized and involves no mysteries beyond the comprehension of the
layman. In the present chapter is outlined the development of vitamine
testing together with a discussion of some of the deficiencies and the
problems for the future that these deficiencies suggest.

When Casimir Funk made his original studies of the chemical fractions of
an alcohol extract of rice polishings he utilized a discovery of the Dutch
chemist Eijkman. We have already referred to this discovery, viz., that by
feeding polished rice to fowls or pigeons they could be made to develop a
polyneuritis which is identical in symptoms and in response to the
curative action of vitamine, to the beri-beri disease. A normal pigeon can
be made to eat enough rice normally to develop the disease in about three
weeks. The interval can be somewhat shortened by forced feeding. As soon
as the symptoms develop the bird is ready to serve as a test for the
presence or absence of the antineuritic vitamine. If at this time we have
an unknown substance to test it can be administered by pushing down the
throat or mixed with the food or an extract can be made and administered
intravenously. If the dose is curative, the bird will show the effect by
prompt recovery from all the symptoms of the disease in as short a time as
six to eight hours. Such a procedure provides a qualitative test which can
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