THE SILKWORM-DISEASE. 145 



of corpuscles. Such moths as were formed, and which 

 emerged from their cocoons, had a most miserable ap- 

 pearance. The disease sometimes went so far as to 

 render breeding and the laying of eggs impossible. 



Faithful to the rules prescribed by the experi- 

 mental method, Pasteur was careful to reproduce 

 these same experiments with the worms of the 

 standard lot, from which all infected worms had 

 been selected. He fed these healthy worms on leaves 

 over which a clear infusion made from the remains of 

 moths or worms exempt from corpuscles had been 

 spread with a paint-brush, instead of leaves conta- 

 minated with corpusculous remains. This food kept 

 the worms in their usual health. Could there be a 

 better proof that the corpuscles alone were the real 

 cause of the pebrine disease ? 



These experiments, I repeat, threw a strong light 

 on the nature of the disease, and exactly accounted 

 for what took place in the industrial cultivations. 

 From the malady which attacked the worms at their 

 birth, decimating a whole cultivation, down to the 

 invisible disease that may be said to inclose itself 

 in the cocoon, all was now explained. One of the 

 effects of the plague which had most excited the sur- 

 prise and thwarted the efforts of cultivators was the 

 impossibility of finding productive eggs, even when 

 they tried to obtain them from the cocoons of groups 

 which had succeeded perfectly well as far as the pro- 



