246 CRITIQUES AND ADDRESSES. [x. 



the portion of a vast population which, in former days, 

 was industrious and well-to-do. 



Tri 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 Keport 1 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 silkworm is, in every respect, comparable to the 

 cholera among mankind. But it differs from the cholera, 

 and so far is a more formidable malady, in being here- 

 ditary, and in beiDg, under some circumstances, conta- 

 gious as well as infectious. 



The Italian naturalist, Filippi, discovered in the blood 

 of the silkworms affected by this strange disorder a multi- 

 tude of cylindrical corpuscles, each about ^Vo of an mcn 

 long. These have been carefully studied by Lebert, and 

 named by him Panliistophyton ; 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 con- 

 comitants, of the disease 1 Some naturalists took one 

 view and some another ; and it was not until the French 

 Government, alarnled by the continued ravages of the 

 malady, and the inefficiency of the remedies which had 

 been suggested, despatched M. Pasteur to study it, that 

 the question received its final settlement ; at a great 

 sacrifice, not only of the time and peace of mind of 

 that eminent philosopher, but, I regret to have to add, 

 of his health. 



1 " Etudes sur les Maladies actuelles dcs Vers a Sole," p. 53. 



