208 LOUIS PASTEUR. 



deny the existence of parasitic diseases, yet, in his 

 opinion, the microbes were the effect and not the cause 

 of these diseases. 



'Is it possible,' cried Pasteur, who was present at 

 the meeting, ' that at this day such a scientific heresy 

 should be held ? My answer to Dr. Bastian will be 

 short. Take the limb of an animal and crush it in a 

 mortar ; let there be diffused in this limb, around these 

 crushed bones, as much blood, or any other normal or 

 abnormal liquid as you please. Take care only that 

 the skin of the limb is neither torn nor laid open, and 

 I defy you to exhibit on the following day, or during 

 all the time the malady lasts, the least microscopic 

 organism in the humours of this limb.' 



After the example of Liebig in 1870, Dr. Bastian 

 did not accept the challenge. 



But if a disease like splenic fever is carried by a 

 microbe, this microbe is under the influence of the 

 medium in which it finds itself. It does not develop 

 everywhere. Easily inoculable and fatal to the ox, 

 the sheep, the rabbit, and the guinea pig, splenic fever 

 is very rare in the dog and in the pig. These must 

 be inoculated several times before they contract the 

 disease, and even then it is not always possible to 

 produce it. Again, there are some creatures which are 

 never assailable by it. It can never be taken by fowls. 

 In vain they are inoculated with a considerable quan- 

 tity of splenic blood; it has no effect upon them. 



