206 LOUIS PASTEUR. 



field of the microscope, nothing is now seen but a dust 

 of brilliant isolated specks, upon which the oxygen of 

 the air has no action. It is thus that a dust of septic 

 germs can be formed even in contact with air. And 

 thus it becomes possible to understand how anaerobic 

 organisms may be sown in putrescible liquids by the 

 dust suspended in the atmosphere. Thus also may 

 be explained the permanence of putrid diseases, even 

 of those which are caused by anaerobic microbes, that 

 cannot live in the atmosphere and which escape de- 

 struction by becoming spores. 



By means of these experiments, as unexpected as 

 they were conclusive, Pasteur had demonstrated that 

 Jaillard and Leplat had not really inoculated their 

 rabbits with an amorphous virus, liquid or solid, but 

 with a virus constituted of a living microscopic organ- 

 ism in other words, with a true ferment. By the 

 side of the parasite of splenic fever we have thus a 

 fresh example of a living animated virus, with germs 

 forming dust. And the extraordinary thing is that 

 among the microbes of special maladies which they 

 produce by penetrating and multiplying in the bodies 

 of animals are to be found aerobies like the bacilli of 

 splenic fever, and anaerobies like the vibrios of acute 

 septicaemia. 



