338 THE CANADIAN NATURALIST. [Sept. 



Silkworms are liable to many diseases ; and even, before 1853. 

 a peculiar epizootic, frequently accompanied by the appearance of 

 dark spots upon the skin (whence the name of " Pebrine" which 

 it has received), had been noted for its mortality. But in the 

 years following 1853 this malady broke out with such extreme 

 violence, that, in 1856, the silk-crop was reduced to a third of the 

 amount which it had reached in 1853 ; and, up till within the last 

 year or two, it has never attained half the yield of 1853. This 

 means not only that the great number of people engaged in silk- 

 growiug are some thirty millions sterling poorer than they might 

 have been ; it means not only that high prices have had to he paid 

 for imported silk-worm-eggs, and that, after investing his money 

 in them, in paying for mulberry-leaves and for attendance, the 

 cultivator has constantly seen his silk-worms perish and himself 

 plunged in ruin, — but it means that the looms of Lyons have 

 lacked employment, and that, for years, enforced idleness and 

 misery have been the portion of a vast population which, in former 

 days, was industrious and well to do. 



In 1858 the gravity of the situation caused the French Academy 

 of Sciences to appoint Commissioners, of whom a distinguished 

 naturalist, M. de Quatrefages, was one, to inquire into the nature 

 of this disease, and, if possible, to devise some means of staying 

 the plague. In reading the Report (Etudes sur les Maladies 

 Actuelles des Vers a Soie, p. 53) made by M. de Quatrefages, in 

 1859, it is exceedingly interesting to observe that his elaborate 

 study of the Pebrine forced the conviction upon his mind that, in 

 its mode of occurrence and propagation, the disease of the silk- 

 worm is, in every respect, comparable to the cholera among man- 

 kind. But it differs from the cholera, and, so far, is a more 

 formidable disease, in being hereditary, and in being under some 

 circumstances contagious, as well as infectious. 



The Italian naturalist, Filippi, discovered in the blood of the 

 silkworm affected by this strange disease, a multitude of cylindri- 

 cal corpuscles, each about ^ooo of an inch long. These have been 

 carefully studied by Lebert, and named by him Panhistophyton ; 

 for the reason that, in subjects in which the disease is strongly 

 developed, the corpuscles swarm in every tissue and organ of the 

 body, and even pass into the undeveloped eggs of the female moth. 

 But are these corpuscles causes, or mere concomitants, of the 

 disease ? Some naturalists took one view and some another ; and 

 it was not until the French Government, alarmed by the continued 



