ON DUST AND DISEASE. 143 



annees.' Pasteur heard the buzz, but he continued his 

 work. In choosing the eggs intended for incubation, 

 the cultivators selected those produced in the successful 

 6 educations ' of the year. But they could not under- 

 stand the frequent and often disastrous failures of their 

 selected eggs ; for they did not know, and nobody prior 

 to Pasteur was competent to tell them, that the finest 

 cocoons may envelope doomed corpusculous moths. It 

 was not, however, easy to make the cultivators accept 

 new guidance. To strike their imagination, and if 

 possible determine their practice, Pasteur hit upon the 

 expedient of prophecy. In 1866 he inspected, at St. 

 Hippolyte-du-Fort, fourteen different parcels of eggs 

 intended for incubation. Having examined a sufficient 

 number of the moths which produced these eggs, he 

 wrote out the prediction of what would occur in 1867, 

 and placed the prophecy as a sealed letter in the hands 

 of the Mayor of St. Hippolyte. 



In 1867 the cultivators communicated to the mayor 

 their results. The letter of Pasteur was then opened 

 and read, and it was found that in twelve out of fourteen 

 cases there was absolute conformity between his pre- 

 diction and the observed facts. Many of the groups 

 had perished totally ; the others had perished almost 

 totally ; and this was the prediction of Pasteur. In 

 two out of the fourteen cases, instead of the prophesied 

 destruction, half an average crop was obtained. Now, 

 the parcels of eggs here referred to were considered 

 healthy by their owners. They had been hatched and 

 tended in the firm hope that the labour expended on 

 them would prove remunerative. The application of 

 the moth-test for a few minutes in 1866, would have 

 saved the labour and averted the disappointment. Two 

 additional parcels of eggs were at the same time sub- 

 mitted to Pasteur. He pronounced them healthy ; and 



