FOR THE NATIONAL WEALTH 87 



takes, its hopes, and its discouragements, sur- 

 rounded by the indifference and the hostility 

 of those whose interests it disturbed, and the 

 final triumph, assured, indisputable and univer- 

 sally acclaimed. 



At the very beginning Pasteur made the mis- 

 take of thinking that the corpuscles were the 

 result of pebrine and that they did not make 

 their appearance until the disease had reached 

 a certain stage. But, notwithstanding that he 

 was wrong in this, he established the fact that 

 corpusculous moths produced corpusculous 

 eggs, and that the whole problem was to find a 

 way of obtaining healthy eggs. In this way he 

 opened up the path to the truth. After ex- 

 periments of unimagined delicacy which -de- 

 manded ceaseless watchfulness, Pasteur con- 

 vinced himself that the corpuscles were not an 

 effect of the disease, but its cause, a form of 

 parasite that invaded the bodies of the silk- 

 worms. He proved that pebrine was hereditary 

 and contagious, and that the variations that 

 were shown to occur in the disease were due 



