OTHER DISEASES OF DOMESTIC ANIMALS. 155 



ferments of unhealthy silkworms do not suffice to 

 destroy the bacteria of the leaves, nor to neutralize 

 their injurious effects. 



These bacteria are really the cause of the disease, 

 for if even a minute quantity of the leaves taken from 

 the intestine of diseased silkworms be given to healthy 

 specimens, they soon die of the same disease. It is, 

 therefore, essentially contagious, and in order to prevent 

 the diseased silkworms from contaminating the healthy 

 by soiling the leaves on which the latter are about to 

 feed, as much space should be assigned to them as 

 possible. 



Good seed should also be selected, since it has been 

 ascertained that some lots of seed are more liable to 

 the disease than others. The affection does not indeed 

 begin in the egg, as in pebrine, but the question of 

 heredity comes in. It is clear that when a silkworm 

 has been affected by flacherie without dying of it, its 

 eggs will have little vitality, and the grubs which issue 

 from them will be predisposed by their feeble constitu- 

 tion to contract the disease. 



