2 W. T. SEDGWICK 



was able to magnify microscopic into macroscopic characteristics, 

 and for the first time made it practicable to differentiate and 

 classify bacteria with some accuracy. It should also be remem- 

 bered that Pasteur's disciple and follower, Joseph Lister, 

 made improvements in the method of pure culture by ''dilution" 

 during his studies upon milk and the lactic fermentation, 



Pasteur, very early in his work, had insisted upon the indis- 

 pensabiUty of the microscope in all investigations of yeasts and 

 other microbes, as well as in fermentations, putrefactions and 

 diseases (of wine and beer), which they produce, and only those 

 who have taken the trouble to read the preposterous paper in 

 which Liebig, the most eminent chemist and fermentation expert 

 of his day, ridicules the use of the microscope — a paper which 

 Huxley has rightly pronounced the most surprising that ever 

 appeared in a sober scientific journal — can appreciate the 

 immense service done by Pasteur in developing the microscope 

 as an instrument of research. It was his insistence upon the 

 use of the microscope superadded to a rigid and refined technique 

 all along the line which enabled him to win one of the hardest 

 fought and most important scientific battles of the nineteenth 

 century, namely, that on behalf of biogenesis. 



Pasteur is thus at once the pioneer and the founder of that 

 wonderful science of which the present new Journal is to stand 

 as an American exponent. 



But it is very doubtful if bacteriology would ever have at- 

 tained even a tithe of its present development and importance 

 if the methods of Pasteur and Lister had not been supplemented 

 and largely displaced by those of Robert Koch, who is at once the 

 protagonist of the new science and the architect of that imposing 

 superstructure now known as bacteriology, built chiefly since 

 1881 by Koch himself and his pupils upon the foundations laid 

 by Pasteur. 



In his earUer work, Koch employed substantially the methods 

 of liquid culture of Pasteur and Lister, but before long he vastly 

 improved upon these cultures by thickening them with gelatine 

 or agar — a step to which he was led through the use of potato 

 an opaque medium for which it was obviously desirable to sub- 



