Autograph letter signed ("L. Pasteur").
8vo (200 x 130 mm). 1 p.
In French, to an unidentified correspondent: "I do not believe at all that age or youth influences the results of vaccination. If accidents occurred during the night of the vaccination, whatever the age of the individual, it was the result of impure vaccine or due to a wrongly performed procedure".
Yellowing, small marginal tears skilfully repaired.