Source : Webster's Revised Unabridged Dictionary (1913)

Pasteur's fluid \Pas`teur's" flu"id\ (Biol.)
   An artificial nutrient fluid invented by Pasteur for the
   study of alcoholic fermentation, but used also for the
   cultivation of bacteria and other organisms. It contains all
   the elements of protoplasm, and was originally made of the
   ash of yeast, some ammonia compound, sugar, and water.