Summary of Studies by Cohn and Collaborators

From such studies, Cohn, McMeekin, and Minot in 1930 (18, 19) believed that the active principle was a nitrogenous base, the nitrogen in which exists as in a secondary or tertiary amine. The low nitrogen content (10.8 per cent) appeared to exclude purine ot pyrimidine bases, but not ring compounds of the pyrrole or pyridine types. It seemed unlikely that it was a pyrrole because it gave no pine-splinter test characteristic of certain pyrroles. 

In summary, one of their tables is reproduced to illustrate the outstanding progress they made in the method of fractionation, purification, and understanding of the nature of the active principle effective in pernicious anemia (19) (Table II). 

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