INTRODUCTION XXIX 



bring into the light of day that which was good in the 

 most confused conceptions. 



"Duclaux was, above all things, an independent. He 

 esteemed scientific doctrines according to their fecundity 

 without believing them final and thought usually that 

 the fruitful periods of science are those wherein dogmas 

 are shaken. His knowledge was truly encyclopaedic; 

 Duclaux had studied to the bottom the mathematical and 

 physical sciences and was quick to understand all the 

 others. Thus he was capable of writing a book like his 

 Traite de Microbiologie, and of treating with competence 

 subjects pertaining to physics and to medicine. The 

 readers of these Annales have had the proof many times 

 in the critical reviews where he developed a question 

 with remarkable precision and ease. I need not recall 

 to them the qualities of Duclaux the WTiter. No scien- 

 tific man of his time has written better than he, no one 

 has better employed his talent. 



"Duclaux was an incomparable professor. His facility 

 of speech never served to mask the difficulties of a sub- 

 ject; he went to the bottom of things without fatiguing 

 the attention, because with him everything became easy 

 to understand. His lectures have determined more than 

 one vocation and provoked numerous investigations. 

 He sow^ed ideas and rejoiced to see them germinate in the 

 fields of others. 



''The regrets inspired by the loss of such a man will be 

 extinguished only with those who have know^n him. 

 But the esteem and the admiration for Duclaux will be 

 durable, for his works will be there to attest that he was a 

 scientific man of the first order and, what is much more 

 rare, a noble character." 



I have ventured to add to the book a few footnotes 

 indicating progress in certain fields of research, an index, 



