DISEASES OF SILKWORMS. 



2 g 





of tin- disease; the internal signs are oval corpuscles only risible through 

 the microscope. 



Worms healthy born may contract pebrine during life, but this may 



not prevent their spinning, as the disease does not reach it- climax 

 before the chrysalid or moth stage, and in its incipiency the worm is 



strong enough to spin, though the moth will produce diseased 

 Hence the necessity of repeating the microscopical examination for 

 each generation of worms. 



Pebrine is not always visible, 

 and when latent induces other 

 diseases. When only one crop 

 of cocoons is made annually, it 

 is comparatively easy to resist 

 pebrine. as the germ of it. out- 

 side of an egg, retains its vitality 

 not longer than seven months. 

 The disease takes thirty days to 

 develop: therefore, if worms 

 from pebrinized egg> can be 

 made to spin within twenty- 

 five days after hatching, they 

 may yield a fair harvest of 

 cocoons. In any case, however, 

 it is only safe to use pure eggs, 

 as pebrine, even in undeveloped 

 stages, renders the worm more 

 liable to contract all other dis- 

 eases. 



FLACHERIE, OR FLACCIDITY. 



This is now the most dreaded 

 disease among European silk- 

 worms. In general, worms are 

 struck with it after their fourth 

 molt, when they are mature, or 

 even while spinning (tig. 12). 



Without any apparent cause, they begin to Languish, then remain 

 completely still, and shortly die. They blac-kon after death (fig. 13), 

 and give out a disagreeable odor. Often entire chamber- perish in a 

 day. Again, the progress of the disease may be alow, the worms even 

 spinning their cocoons, but. dying m the chrysalid state, they putrify 

 and soil the cocoon, thus greatly diminishing the value oi the harvest 

 Flachene is but another name for indigestion. Pasteur and many 

 other scientist- assert that Hacherie is due to ferments and vibrioni 

 developing in the intestinal canal of the worm; other authorities main- 

 tain that the disease may exist independently of these. However, as 



Worms affected with Bacherie dying in the 



t>ru>h i after Pasteur). 



