Vitamin B 12

Year by year, the number of B vitamins increases. B 10 and B 11 are required by chicks, the former for proper feathering, the latter for growth. From liver it has been possible to isolate a pink crystalline substance which can be used to cure pernicious anemia. Folic acid is useful in this disease, for it has a hematopoietic effect (that is to say, it favors increased production of blood cells), but it does not correct the nervous symptoms of the disease. These depend on degenerative changes in the nervous system. Vitamin B 12 in tiny amounts has been thought to correct diseases of both blood and nervous systems, but apparently if the nervous system is badly affected, it can not be cured. The vitamin has been crystallized. It contains 4-4.5 per cent cobalt and also phosphorus; the molecular weight is approximately 1500. (Estimates vary from 1300 to 1600.) In liver extracts there are really two active substances with slightly different absorption spectra. One of these is the definitive B 12, the other is B 12b. (B 12a is another similar substance derived from B 12 by hydrogenation.)

Vitamin B 12 is apparently identical with what has been called "animal protein factor." This was originally obtained from such diverse sources as milk, muscle, liver and cow manure. Although called animal protein factor, it can likewise be obtained from plant sources. Both animal protein factor and vitamin B 12 promote growth in some bacteria, in chickens, rats and mice. The effect on growth may be due to the fact that the vitamin seems to increase the utilization of amino acids. At any rate, this has been reported for chicks.