224 PASTEUR: THE HISTORY OF A MIND 



of soil which my hothouses cover. These few cubic 

 meters of air, these few square meters of the surface 

 of the soil weie there in the midst of a possibly universal 

 contagion, and they withstood it for a period of many 

 months. But of what service would the shelter of the 

 hothouses be in the case of disease and death caused by 

 the Mucor parasites? Not the least! Since the para- 

 sites of the saccharomyces reach the surface of the grapes 

 at a definite period of the year, a shelter, put on in time, 

 was able to keep them free from these germs, as Europe 

 is protected from the cholera and the plague by quaran- 

 tines. The Mucor parasites, on the contrary, being 

 present during the whole year in the soil of our fields 

 and our vineyards, were necessarily under the hothouses 

 when they were put up, like, in some respects, the germs 

 of our common contagious diseases, against which the 

 quarantines opposed to cholera, yellow fever, or the 

 plague are ineffectual. 



"Must we not believe, by analogy, that a day will 

 come when preventive measures, of easy application, 

 will arrest these plagues which at one blow desolate 

 and terrify whole populations, as did the yellow fever 

 in its recent invasion of the Senegal and the valley of 

 the Mississippi, or the bubonic plague which has raged 

 on the shores of the Volga." 



These few lines form the introduction to a new life. 

 They show the preoccupations which had just taken 

 possession of Pasteur's mind and which already com- 

 pletely filled it. They were written in 1S79, when the 

 studies of anthrax and of chicken cholera were already 

 begun. They form the connecting link between the 

 old labors and the new, and it is for this reason that I 

 have transcribed them. I .should be very much aston- 

 ished if the reader has not noted their resolute manner 

 of expression and their i)rophetic tone. 



