1865—1870 117 



to scratch. But of all those names, that of " purine " 

 adopted by Quatrefages was the most general. It came from 

 the patois word pebre (pepper). The spots on the diseased 

 worms were, in fact, rather like pepper grains. 



The first symptoms had been noticed by some in 1845, by 

 others in 1847. But in 1849 it was a disaster. The South of 

 France was invaded. In 1853, seed had to be procured from 

 Lombardy. After one successful year the same disappoint- 

 ments recurred. Italy was attacked, also Spain and Austria. 

 Seed was procured from Greece, Turkey, the Caucasus, but 

 the evil was still on the increase; China itself was attacked, 

 and, in 1864, it was only in Japan that healthy seed could be 

 found. 



Every hypothesis was suggested, atmospheric conditions, 

 degeneration of the race of silkworms, disease of the mulberry 

 tree, etc. — books and treatises abounded, but in vain. 



When Pasteur started for Alais (June 16, 1865), entrusted 

 with this scientific mission by the Minister of Agriculture, his 

 mind saw but that one point of interrogation, " What caused 

 these fatal spots?" On his arrival he sympathetically ques- 

 tioned the Alaisians. He received confused and contradictory 

 answers, indications of chimerical remedies ; some cultivators 

 poured sulphur or charcoal powder on the worms, some mus- 

 tard meal or castor sugar; ashes and soot were used, quinine 

 powders, etc. Some cultivators preferred liquids, and syringed 

 the mulberry leaves with wine, rum or absinthe. Fumiga- 

 tions of chlorine, of coal tar, were approved by some and 

 violently objected to by others. Pasteur, more desirous of 

 seeking the origin of the evil than of making a census of these 

 remedies, unceasingly questioned the nursery owners, who in- 

 variably answered that it was something like the plague or 

 cholera. Some worms languished on the frames in their earliest 

 days, others in the second stage only, some passed through the 

 third and fourth moultings, climbed the twig and spun their 

 cocoon. The chrysalis became a moth, but that diseased moth had 

 deformed antennse and withered legs, the wings seemed singed. 

 Eggs (technically called seed) from those moths were inevitably 

 unsuccessful the following year. Thus, in the same nursery, 

 in the course of the two months that a larva takes to become 

 a moth, the pebrine disease was alternately sudden or in- 

 sidious : it burst out or disappeared, it hid itself withis the 

 chrysalis and reappeared in the moth or the eggs of a moth 



