156 THE LIFE OF PASTEUR 



tised seeding according to his rigorous prescriptions had met 

 with complete success. Other silkworm cultivators, less well 

 advised, duped by the decoying appearances of certain broods, 

 had not taken the trouble to examine whether the moths were 

 corpuscled ; they were witnesses and victims of the failure 

 Pasteur had prophesied. He now looked upon pebrine as con- 

 quered; but flachery remained, more difficult to prevent, being 

 greatly dependent upon the accidents which traverse the life of 

 a silkworm. Some of those accidents happen in spite of all 

 precautions, such as a sudden change of temperature or a 

 stormy day ; but at least the leaves of the mulberry tree could be 

 carefully kept from fermentation, or from contamination by 

 dusts in the nurseries. Either of those two causes was suf- 

 ficient to provoke a fatal disorder in silkworms, the feeding of 

 which is so important that they increase to fifteen thousand 

 times their own weight during the first month of their life. 

 Accidental flachery could therefore be avoided by hygienic pre- 

 cautions. In order to prevent it from becoming hereditary, 

 Pasteur who had pointed out that the micro-organism which 

 causes it develops at first in the intestinal canal of the worm 

 and then becomes localized in the digestive cavity of the chry- 

 salis advised the following means of producing a healthy 

 strain of silkworms: "This means," writes M. Gernez, 

 Pasteur's assiduous collaborator in these studies, "does not 

 greatly complicate operations, and infallibly ensures healthy 

 seed. It consists in abstracting with the point of a scalpel a 

 small portion of the digestive cavity of a moth, then mixing 

 it with a little water and examining it with a microscope. If 

 the moths do not contain the characteristic micro-organism, the 

 strain they come from may unhesitatingly be considered as 

 suitable for seeding. The flachery micro-organism is as easily 

 recognized as the pebrine corpuscle." 



The seed merchants, made uneasy by these discoveries which 

 so gravely jeopardized their industry, spread the most slan- 

 derous reports about them and made themselves the willing 

 echo of every imposture, however incredible. M. Laurent 

 wrote to his daughter, Madame Pasteur, in a letter dated from 

 Lyons (June 6) : " It is being reported here that the failure of 

 Pasteur's process has excited the population of your neighbour- 

 hood so much that he has had to flee from Alais, pursued by 

 infuriated inhabitants throwing stones after him." Some of 

 these legends lingered in the minds of ignorant people. 



