SKETCH OF M. LOUIS PASTEUR. 825 



reader, and accompanied by a logic equally severe, restored the con- 

 viction that, even in these lower reaches of the scale of being, life does 

 not appear without the operation of antecedent life. The main posi- 

 tion of Pasteur, though often assailed, has never yet been shaken. It 

 has, on the contrary, been strengthened by practical researches of the 

 most momentous kind. He has applied the knowledge won from 

 his inquiries to the preservation of wine and beer, to the manufact- 

 ure of vinegar, to the staying of the plague which threatened utter 

 destruction to the silk-husbandry of France, and to the examination of 

 other formidable diseases which assail the higher animals, including 

 man. His relation to the improvements which Professor Lister has 

 introduced into surgery is shown by a letter quoted in his ' Etudes sur 

 la Biere.' Professor Lister there expressly thanks Pasteur for having 

 given him the only principle which could have conducted the antiseptic 

 system to a successful issue." 



The most highly appreciated of Pasteur's earlier researches be- 

 cause they most closely touched the economical interests of his coun- 

 try, and had a direct bearing on the prosperity of one of its great 

 industries were those which he made upon the disease of the silk- 

 worm. A plague had raged among the silk-worms of France for 

 fifteen years. The revenue from silk-culture had doubled itself during 

 the twenty years before 1853, and appeared at that time likely to con- 

 tinue to increase. Then disaster suddenly fell on the business, and 

 the production of cocoons fell from twenty-six million kilogrammes in 

 1853, in the course of twelve years, to four million kilogrammes, the 

 fall entailing, in the single year last mentioned, a loss of one hun- 

 dred million francs, or twenty million dollars. Dumas, the chem- 

 ist, whose home lay in the district that was most afflicted by the 

 scourge, asked Pasteur, with almost a personal interest in the matter, 

 to undertake the investigation of the malady. Pasteur, says Professor 

 Tyndall, at this time had never seen a silk-worm, and he urged his 

 inexperience in reply to his friend. But Dumas knew too well the 

 qualities needed for such an inquiry to accept Pasteur's reason for de- 

 clining it. " I put," he said, " an extreme value on seeing your atten- 

 tion fixed on the question that interests my poor country ; the misery 

 surpasses all that you can imagine." The disease had been called 

 p'ebrine by M. de Quatrefages, a name which Pasteur adopted ; it was 

 outwardly manifested by black spots on the bodies of the caterpillars, 

 and also declared itself in their stunted and unequal growth, the lan- 

 guor of their movements, their fastidiousness toward food, and their 

 premature death. It had already been discovered that the unhealthy 

 worms were afflicted with peculiar corpuscles in enormous numbers, 

 which were also sometimes found in the eggs, and which were con- 

 nected with the disease. Pasteur directed his attention to these cor- 

 puscles, and proved that they might be incipient in the egg, and escape 

 detection, and that they might also be germinal in the worm, and still 



