THE SILKWOEM-DISEASE. 157 



A Chinese book published on the rearing of silk- 

 worms contains a series of little practical counsels. 

 * The person who takes care of the silkworms,' says 

 this guide to the perfect cultivator, ' ought to wear f a 

 simple garment, not lined. He must regulate the 

 temperature of the spinning-house according to the 

 sensation of heat or cold which he experiences ; if he 

 feels cold, he may conclude that the worms are cold, 

 and he will increase the fire ; if he feels hot, he will 

 conclude that the worms are hot, and he will suitably 

 diminish the fire.' 



One point which had been ignored before the ex- 

 periments of Pasteur was the contagious character of 

 ftacherie. This contagion may surpass that of pelrine 

 itself as regards duration. In pebrine the dried cor- 

 pusculous matter loses all virulence after the lapse 

 of some weeks. The disease cannot, therefore, com- 

 municate itself from one year to another by the cor- 

 pusculous dust of a rearing establishment. The germs, 

 on the contrary, of the microscopic organisms which 

 provoke fermentation in the mulberry leaves, especially 

 the vibrios, retain their vitality for several years. The 

 dust of a silkworm nursery infected by flacherie ap- 

 pears under a microscope quite full of cysts or spores 

 of vibrios. These spores or cysts rest, like the sleep- 

 ing beauty in the forest, until a drop of water falls 

 upon them and awakens them into life. Deposited 

 on the leaves which are to serve as nourishment, 



