VIII BIOGENESIS AND ABIOGENESIS 267 



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 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. 



But the sacrifice has not been in vain. It is 

 now certain that this devastating, cholera-like, 

 Pebrine, is the effect of the growth and multiplica- 

 tion of the Panhistophyton in the silkworm. It is 

 contagious and infectious, because the corpuscles 

 of the Panhistophyton pass away from the bodies 

 of the diseased caterpillars, directly or indirectly, 

 to the alimentary canal of healthy silkworms in 

 their neighbourhood ; it is hereditary because the 

 corpuscles enter into the eggs while they are being 

 formed, and consequently are carried within them 

 when they are laid ; and for this reason, also, it 

 presents the very singular peculiarity of being 

 inherited only on the mother's side. There is 

 not a single one of all the apparently capricious 

 and unaccountable phenomena presented by the 

 Pebrine, but has received its explanation from the 

 fact that the disease is the result of the presence 

 of the microscopic organism, Panhistophyton. 



