150 Blilletin of 'Laboratories of Denison Uiiiversity voi. xi] 
influenced by Pasteur’s great discoveries in the field of fermen- 
tation. Duclaux^ in 1878, lent support to Cohn’s conclusion 
in that he found that cheese made from sterilized milk failed to 
ripen. This certainly appeared as conclusive proof that the 
phenomenon in question was due to germs, although it is now 
certain that his results were due to quite different causes. 
Soon other experimenters followed in this newly opened field, 
whose results quite uniformly lent support to the fermentation 
theory. 
Swiss or Emmenthaler cheese was examined microscop- 
ically by Benecke^ and was found to contain a certain bacil- 
lus especially abundant during the ripening stage, which he 
considered as the particular germ that ripened the cheese. 
About the same time methods for isolating germs and growing 
them in pure cultures were being discovered, and Duclaux,'^ 
making use of these, succeeded in isolating ten species of bac- 
teria from cheese, seven of which he found to be aerobes, and 
three anaerobes. He designated these as Tyrothrix forms, 
because of their occurrence in chains or threads. All these 
germs were peptonizers, in that they liquefied gelatin and 
digested the casein of milk. A peptonizing ferment was 
also isolated from the products of their growth, which changed 
the casein of cheese into soluble peptones. Thus his theory 
appeared established on a secure foundation. 
However the above work antedates the discovery of solid 
media such as gelatin and agar, and a doubt may be expressed 
as to the validity of this work. From our present knowledge 
of cheese bacteria, it appears quite remarkable that all these 
separate forms should have such similar characteristics, and that 
none of the non peptonizers were discovered. True, his meth- 
^ Duclaux, Fabrication, maturation et maladies du fromage de Cantal. 
Annales agromomiques 1878. 
Henecke and Schulze, Untersuchungen iiber den Emmenthaler Kase und 
liber einige andere schweizerische Ivasesorten. Landw. Jahrbucher XVI, pp. 
317-400. 
^ DuclauXj Le Lait, etudes chemiques et microbiologiques, Paris 1887. 
(Deuxieme tiragu augmenta 1894.) 
