THE SILKWORM-DISEASE. 159 



salides, and the moths destined to produce the eggs. 

 Every attention should be directed to the complete 

 exclusion of ferments from the intestinal canal of the 

 worms, and from the stomach-pouch of the chrysalides 

 a little pouch to which the intestinal canal of the worm 

 is reduced, with its contents more or less transformed. 

 But if there is not time to make this examination for 

 parasitic ferments with the microscope, a simple in- 

 spection of the worms in their last stage will suffice. 

 Pasteur laid great stress upon the observation of the 

 worms when they climbed on to the heather. 



' If I were a cultivator of silkworms,' he wrote in 

 his beautiful work on the diseases of silkworms, 'I 

 would never hatch an egg produced from worms that 

 I had not observed many times during the last days 

 of their life, so as to make sure of their vigour at the 

 moment when they spin their silk. If you use eggs 

 produced by moths the worms of which have mounted 

 the heather with agility, have shown no signs of 

 flaclierie between the fourth moulting and mounting 

 time, and do not contain the least corpuscle of pebrine, 

 then you will succeed in all your cultivations.' 



III. 



We have now arrived at the end of this long in- 

 vestigation. All the obscurity which enveloped the 

 origin of the diseases of silkworms had now been dis- 



