216 LOUIS PASTEUR. 



death of the animal upon which it lives and multiplies, 

 but which can carry death to other species inoculated 

 with it. Fowls and rabbits living among the guinea- 

 pigs suffering from these abscesses might in a moment 

 be smitten and perish, while the health of the guinea- 

 pigs remained unchanged. To produce this result it 

 would suffice that a little of the discharge from the 

 abscess of a guinea-pig should get smeared over the 

 food of the fowls and rabbits. An observer witnessing 

 such deaths without apparent cause, and ignorant of 

 this strange dependency, would no doubt be tempted 

 to believe in the spontaneity of the disease. He would 

 be far from supposing that the evil had originated in 

 the guinea-pigs, which were all in good health. In 

 the history of contagia what mysteries may some day 

 be cleared up by even more simple solutions than this 

 one ! 



When some drops of the liquid containing this 

 microbe are placed on the food of fowls, the disease 

 penetrates by the intestinal canal. There the little 

 organism increases in such great abundance that ino- 

 culation with the excrements of the injected fowls pro- 

 duces death. It is thus easy to account for the mode 

 of propagation of this very serious disease, which 

 depopulates sometimes all the poultry yards in the 

 country. The only means of arresting the contagion 

 is to isolate, for a few days only, the fowls and the 

 chickens, to remove the dung heaps, to wash the yard 



