SERGEI VORONOFF (1866-1951) Russian-French surgeon, specialized in grafting animal glands into the human body, experimented with testicle transplants as a means to rejuvenation, and wrote on his theory connecting gland secretions with senility. A.L.S. on Laboratory of Special Surgery letterhead, 1p. 8vo., Paris, 1921, apparently flattering, friendly content to an inspector general. Receiving stamp affects one word of text, else very good. Rare! $300-400