Portrait of Louis Pasteur (1822-1895) taken from the Illustrated London News of 1895. A French chemist, he is better known for his achievements in biology & medicine. Pasteurization, a method of destroying microorganisms by gentle heating, was used by Pasteur while attempting to overcome the premature ageing of wine & beer due to the presence of yeasts. Pasteur's experimentation ended the long debate on spontaneous generation. His 'germ theory' provided an understanding of the nature & communication of infectious diseases. Pasteur is best known for his attenuated rabies vaccine, which provided a cure for this deadly disease.