226 PASTEUR: THE HISTORY OF A MIND 



flamed flasks, when he wishes to cultivate and keep pure 

 a species the condition for the development of which 

 he knows only imperfectly, Aspergillus niger gives 

 admirable cultures, flourishing and pure, in contact with 

 the air, and in liquids and flasks which one has not taken 

 the trouble to sterilize. Consequently, in the presence of 

 every new species, his first care was to try several culture 

 media so as to find that which suited it the best. 



Having this principle of culture in the most favorable 

 medium, Pasteur was also the only one who had the 

 ability to add a proper technique. This was due especially, 

 as we have seen, to the efforts of his assistants: Joubert, 

 Chamberland and Roux. 



Finally, as a last advantage, Pasteur had that of being 

 20 years old in the study of microbes and of having more 

 complete notions about them, their needs, their physi- 

 ology and their morphology, than any of the scientific 

 men of his time. It was because of this that he was 

 able so quickly to catch up with and soon to distance 

 those who had entered before him on this pathway, 

 for at the time when he first took up the study of anthrax 

 in 1876, there had been already several pathogenic mi- 

 crobes discovered, and Koch had just published his 

 famous work on the spore of the anthrax bacteridium. 



To appreciate thoroughly the role and the part of 

 Pasteur in this great question of pathology, one must 

 know the general state of science and of the scientific 

 mind in 1876. 1 That is not as easy as one might believe 

 it to be, considering that we have to go back only a few 

 years. The ideas which had currency in 1840 and even 

 in 1860 on the subject of contagious diseases are so far 

 removed from our own that they have almost the dis- 



1 One may obtain a very good idea of what it was in Germany by 

 reading Nageli's Die niederen Pilze in ihren Beziehungen zu den Infec- 

 tionskrankheiten und der Gesundheitspflege, Munich, 1877. Trs. 



