Vitamin B12Content of Calf Thymus Extract

THYMUS and thymus extracts have been reported by Asher1, Rowntree, Clark and Hanson2, and others using rats as test animals, to have a growth-stimulating effect. Later experiments did not confirm this observation3,4. The conflicting results may have been due to deficient diet given to the control animals of the earlier investigators4, or to the varying value of the calf thymus extracts used. No generally accepted explanation, however, has been found for the growth results. Hammar5was of the opinion that some vitamin of the B group may be a contributing factor.