Bulletin of the Scientific Laboratories of Denison University. 
Vol. XI. Article VII. March, 1899. 
BACTERIA IN CHEESE." 
By John Weinzirl, 
Professor of Bacteriology in the University of New Mexico. 
Within the last few years the literature on our subject has 
accumulated at a rapid rate so that a complete review of the 
work done and results attained would be out of place here ; but 
a brief summary of the historical aspect together with a state- 
ment of the present status of the problem is of interest to most 
readers. 
Up to the time of Pasteur’s memorable studies in fermen- 
tation, the latter process was universally considered as a purely 
chemical phenomenon having no relation to organized life. His 
convincing results opened the way to many new fields of inves- 
tigation, among which was the curing of cheese. The latter 
being considered a species of fermentation was naturally explain- 
ed as due to organisms. Besides this Pasteur had proved that 
the lactic fermentation or souring of milk was due to bacteria. 
What could be more plausible than that the changes occurring 
in ripening cheese should be due to similar causes ? 
Cohn,^ who fell under the influence of Pasteur’s work, 
reopened the cheese problem at the point where the chemists 
had left it, by demonstrating bacteria in the rennet used in 
cheese-making, and concluded on this meager basis that the 
process was due to bacteria. But the first real work in our 
field, which has now become classical, was done by Duclaux, an 
assistant of Pasteur’s and who was, beyond doubt profoundly 
•^'Thesis accepted for degree of Master of Science by the University of New 
Mexico, 1898. Presented at the meeting of the Scientific Association, March 
II, 1899. 
^ Cohn, Ferdinand. Beitrage zur Biologie der Pflanzen, Bd. I, 3 Heft. 
?. 191. 
