258 PASTEUR: THE HISTORY OF A MIND 



of them, it is almost a pure culture of the microbe (Fig. 

 21), while in the blood the rods are rare, more elongated 

 and difficult to find in the midst of the corpuscles; fur- 

 thermore, they enter the blood late in the course of 

 the disease and Davaine had not seen them there. Thus 



Fig. 21. The septic vibrio in the alxloininal serosity and in the blood. 

 In the serosity the forms are variable. In the blood they are long filaments, 

 infrequent and hard to see in the midst of the corpuscles. 



it is that one can just fail of making the most beau- 

 tiful discovery. 



Pasteur, for whom everything was a pretext for micro- 

 scopical study, did not allow this opportunity to escape, 

 and threw himself with his customary ardour into the 

 study of this new microbe. There also, a harvest of 

 facts awaited him. 



