Vere scire est per causas scire." \p=m-\Bacon. Wigand saw micro-organisms develop in fluids after exposure to boiling heat for half an hour, a temperature and time sufficient, he thought, to destroy all germs. Hut the experiments at Koch's laboratory at Berlin prove that individual spores resist a boiling heat for several hours. Wigand's erroneous conclusions were based upon an imperfect sterilization.