VIRULENT DISEASES. 191 



On April 30, 1877, Pasteur read to the Academy 

 of Sciences, in his own name and in that of his 

 fellow-worker, a note in which he demonstrated, this 

 time in a completely unanswerable manner, that the 

 bacilli called bacteria, bacterides, filaments, rods, 

 in a word the bacilli discovered by Davaine and 

 Kayer in 1850, constituted the only agent of the 

 malady. 



A little drop of splenic fever blood, sown in 

 urine or in the water of yeast, previously sterilised 

 that is to say, rendered vnputrescible by contact with 

 air free from all suspended germs produces in a few 

 hours myriads of bacilli or of bacteria. A little drop 

 of this first cultivation sown in a second flask contain- 

 ing the same liquid as the first and prepared with the 

 same precautions as to sterility and purity, shows it- 

 self no less fertile. Finally, after ten or twenty 

 similar cultures the parasite is evidently freed from the 

 substances w r hich the initial drop of blood might carry 

 with it ; yet, if a very small quantity of the last cul- 

 ture is injected under the skin of a rabbit or a sheep, 

 it kills them in tw r o or three days at most, with all the 

 clinical symptoms of natural splenic fever. 



It might be objected that the parasite was associ- 

 ated in the cultivating liquid with some dissolved sub- 

 stance that it had produced during its life and which 

 acted as a poison. Pasteur accordingly transported 

 some cultivating tubes into the cellars of the Observa- 



