298 BIOLOGY AND ITS MAKERS 
treatment the precise culture and capacities which he has 
brought to bear upon them.” 
In 1857 Pasteur went to Paris as director of scientific 
studies in the Ecole Normale, having previously been a 
professor in Strasburg and in Lille. From this time on his 
energies became more and more absorbed in problems of a 
biological nature. It was a momentous year (1857) in the 
annals of bacteriology when Pasteur brought convincing 
proof that fermentation (then considered chemical in its 
nature) was due to the growth of organic life. Again in 1860 
he demonstrated that both lactic (the souring of milk) and 
alcoholic fermentation are due to the growth of microscopic 
organisms, and by these researches he developed the 
province of biology that has expanded into the science of 
bacteriology. 
After Pasteur entered the path of investigation of microbes 
his progress was by ascending steps; cach new problem the 
solution of which he undertook seemed of greater importance 
than the one just conquered. He was led from the discovery 
of microbe action to the application of his knowledge to the 
production of antitoxins. In all this he did not follow his 
own inclinations so much as his sense of a call to service. In 
fact, he always retained a regret that he was not permitted 
to perfect his researches on crystallography. At the age of 
seventy he said of himself: ‘‘If I have a regret, it is that I did 
not follow that route, less rude it seems to me, and which 
would have led, I am convinced, to wonderful discoveries. 
A sudden turn threw me into the study of fermentation, fer- 
mentations set me at diseases, but I am still inconsolable to 
think that I have never had the time to go back to my old 
subject”? (Tarbell). 
Although the results of his combined researches form a 
succession of triumphs, every point of his doctrines was the 
subject of fierce controversy; no investigations ever met 
