"4 PASTEUR 



of the French Senate, and in 1865 was charged with 

 the duty of reporting on the petition of some 3,500 

 ' propridtaires des D^partements s6ricicoles' on an 

 epidemic which had for some years been destroying 

 the silkworms of Southern France. Dumas was a 

 native of Alais, a town of the D^partement Gard, 

 situated in the centre of the silkworm industry, where 

 also the distinguished zoologist Quatrefages was born. 

 Anything that affected Alais affected Dumas ; and the 

 epidemic was destroying the prosperity of his native 

 town. The disease was indeed becoming serious. 

 Already in 1849 the silkworms were sickening. 

 The stage at which the symptoms appeared varied — 

 sometimes the eggs were sterile; at other times the 

 silkworms hatched out but to die. If they survived 

 they became shiny ; black spots showed themselves ; 

 the worms moved with difficulty, refused to eat, and 

 perished; or, if they lived long enough to pupate, 

 the pupa either perished or the moth emerged in an 

 enfeebled state and promptly died. 



Efforts had been made to improve the stock by 

 importing eggs from Spain and Portugal, but the 

 Peninsula was soon affected. Eggs were then fetched 

 from Turkey, Greece, and the adjacent islands. These 

 countries too becoming infected, the French cultivators 

 sent further afield and brought eggs from Syria and 

 the Caucasus. Even this resource failed them, and in 

 1864 every silk-producing country in the world was 

 infected, with the solitary exception of Japan. The 

 loss to commerce was prodigious. In a normal year 

 the value of the cocoons produced in Southern France 

 is, roughly speaking, about ;£"4,ooo,ooo ; in the years 

 1863 and 1864 it had fallen below ;£'i,ooo,ooo. 



When Dumas first asked Pasteur to investigate the 

 disease which was ruining large tracts of the South of 

 France, the latter not unnaturally hesitated. 'Con- 

 siderez, je vous prie, que je n'ai jamais touche un ver 



