Photo: Rischgitz Collection. 



LOUIS PASTEUR 



The great French scientist who passed from work on chemistry to 

 researches on the origin of life, and from these to pioneer experiments 

 in the fields of bacteriology and immunity. 



Photo: Henri Manuel. 



METCHNIKOFF 



The Russian scientist who took up Pasteur's 

 work at the Pasteur Institute in Paris. Perhaps 

 his greatest claim to fame consists in his discover- 

 ies concerning the devouring of foreign particles 

 by the white corpuscles in the blood. 



