INTRODUCTION XVll 



keeping qualities of the properly made cheeses. ''The 

 work of Duclaux inaugurated the scientific era in the 

 dairy industry" (Dr. Roux). In recognition of the im- 

 portance of these researches the Agricultural Society 

 awarded him its great gold medal in 1881. 



Duclaux was also the first to gather together and 

 coordinate the scattered facts on the enzymes. This he 

 did in 1877 for Dr. Dechambre's " Dictionnaire des 

 sciences medicales.^' Some pages sufficed at this time, 

 but in 1899 when he took up the subject again for the 

 second volume of his "Traite," seven hundred and fifty 

 pages were insufficient. ''He returned to this subject 

 many times, showing how the same microscopic organism 

 secretes different enzymes, according to the food that is 

 given it. He classed the enzymes by the reactions 

 they cause and proposed the terminology^ adopted 

 to-day" (Dr. Roux). 



He also devoted much time to the purity of w^ater 

 supplies and to analyzing, especially during vacations in 

 the latter part of his life, the water of springs issuing 

 from the volcanic lands, and said that he could tell 

 whether the water had percolated over limestone or 

 basalt. 



Also toward the close of his life he became greatly 

 interested in community welfare, attended conferences, 

 presided at meetings, made addresses, and wrote the 

 charming book "L'hygiene sociale.'" 



In 1888 when the Pasteur Institute was founded the 

 workers in the rue d'Ulm had only to transport their 

 microscopes and their balances to rue Dutot, but there 

 was need of someone not to make discoveries, all could 

 do that, but to disseminate them and to formulate a body 

 of doctrines. Duclaux was selected for this purpose. The 

 other colleagues of this time were Chamberland, Roux, 

 Nocard; Perdrix, assistant professor; Loir and Fernbach, 



