Pioneering French microbiologist and chemist (1822–1895) who demonstrated the germ theory of disease and developed the first vaccine against rabies. Ink signature, “L. Pasteur,” on 5.75 x 4.5 mailing envelope addressed in another hand to Monsieur Meates and postmarked 1886. Matted with a nineteenth-century engraving and engraved plaque to an overall size of 12 x 20. In very good condition, with opening tears to top edge of envelope and scattered soiling and toning. The signature is dark and mostly unaffected. R&R COA.
