72 SILKWORMS. 



tissues and kill it. This is not the same species as is the cause 

 of the disease muscardine, but it is of a similar nature. 



Muscardine is a contagious disease, i.e., the spores of the 

 fungus, on gaining access to the body of a healthy caterpillar, as, 

 for example, by passing in at the spiracles, will generate the 

 disease ; or even if they settle on the skin they are able to pro- 

 duce fine threads which can penetrate the tissues of the living 

 caterpillar, and so work its ruin. If, therefore, any specimens in 

 a brood become infested with muscardine, it is of importance, not 

 only that they should themselves be removed, but also that the 

 trays and other apparatus should be disinfected, as, for example, 

 by washing with a dilute solution of carbolic acid. There seems 

 to be no cure known for this disease, but the best means of 

 prevention are, as usual, good food, a plentiful supply of pure, 

 dry air, and cleanliness. About fifty years ago great damage was 

 done to the French silk industry by this disease, but thanks to 

 scientific investigations into its origin and cause, and to improved 

 sanitary appliances, it has now almost entirely disappeared. The 

 muscardined caterpillar, though it usually perishes before forming 

 its cocoon, is yet sometimes able to accomplish this task, but the 

 cocoon so produced is not a good one ; it has a sort of waxy 

 semi-transparency, and contains, not a living chrysalis, but the 

 dead and dried-up caterpillar. 



The most terrible of the diseases of the silkworm is pcbrine, or 

 pepper disease, which was formerly called gattine. It has acquired 

 the name of pebrine from the fact that the caterpillars affected 

 with it become covered with a number of black spots, as though 

 they had been sprinkled over with coarsely- powdered black 

 pepper. It is a disease something like cholera, but possesses the 

 terrible distinction of being hereditary. This, of course, in the 

 case of an animal which is, and can only be, bred from one 

 generation to another, and of which there is no wild stock to fall 

 back upon, infinitely increases its disastrous effects. Languor, 

 loss of appetite, and the dark spots are the symptoms of the 

 disease. Its cause is to be found in the presence of extremely 

 minute corpuscles, called psorospennicz. These were first noticed 

 by the French naturalist, Guerin-Meneville, in 1849, DUt it was 

 not then known for certain what was their relation to the disease, 

 and for a long time it was a disputed point whether they were the 

 cause or merely an effect. It remained for the renowned Louis 

 Pasteur, now so well-known by his experiments in connection 

 with hydrophobia, not merely to demonstrate that the disease is 

 entirely dependent upon the presence and multiplication of these 

 corpuscles, but also to show how it might be stamped out. 



