It was to be expected that biochemists would devote themselves assiduously to the intriguing problems of the isolation and identification of the vitamins. Recent years have witnessed considerable progress in this field of research. The purification of vitamin D, for example, has proceeded to a point at which well crystallized active antirachitic substances of surprising potency have been secured. Both German and English investigators have reported the production of purified products of which 1 mg. is equivalent to 40,000 international (rat) units. From yeast, workers1 in the department of biochemistry at Oxford have separated "crystals" that act antineuritically in the conventional pigeon test in daily doses of less than 2 gammas; that is, 0.000002 Gm. This is greater than the activity of other crystalline preparations previously described. The identification of the potent principle in these instances remains to be established.
Even more satisfactory has been the progress in the
RECENT STUDIES OF VITAMIN C. JAMA. 1933;101(6):450–451. doi:10.1001/jama.1933.02740310034013
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