PURE CULTURE FERMENTS. 321 



in others. In isolated instances it is produced by the mecha- 

 nical incorporation of added flavouring substances to the fresh 

 cheese mass. This applies, for instance, to the already men- 

 tioned "Glaraer Schabziger" or herb- cheese (Krauter Kdse), 

 which owes its characteristic aroma to the addition of dried 

 Melilotus ccerulea (blue or Swiss melilot). The English "sage- 

 cheese " and American " clover-cheese " may also be mentioned 

 as examples. 



In many cases the odorous principle is, on the other hand, 

 produced spontaneously in ripening, i.e. by the activity of micro- 

 organisms, of which nothing is as yet definitely known. L. 

 PAMMEL (II.) discovered on cabbage leaves a Bacillus aromaticus 

 which, when inoculated into fresh curd, produces during the 

 ripening process an aroma similar to that of " clover-cheese." 



178. Pure Culture Ferments. 



The results briefly recorded in the preceding paragraph must 

 be regarded as first steps inspiring us to further progress towards 

 the goal of all methods relating to the practical application of 

 Fermentation Physiology, viz., the establishment of control over 

 the progress of fermentation. In the matter of cheese-making the 

 attainment of this desire is still remote, and Mycologists are not 

 yet able to recommend this or that particular microbe with any 

 assurance of success. On the contrary, practice has also in this 

 respect taken the lead by employing in special cases such addi- 

 tions as, without being pure cultures (in a bacteriological sense), 

 nevertheless contain a predominating proportion of the organism 

 most suitable for the object in view. One of the two classes of 

 cheese to which this applies is the Roquefort, the other being 

 Edam cheese. 



Any one examining for the first time the said French cheese 

 (originally prepared in the village of Roquefort (Dep. Aveyron), 

 from unskimmed sheep's milk) will notice the green growth of 

 mould occupying all the cracks abundantly intersecting this brittle, 

 sharp-flavoured mass. This filamentous fungus, whose presence 

 is by no means a sign of unsound composition, has been shown to 

 be the organism known as Penicillium glaucum (described in 

 vol. ii.), which settles in the fissured cheese mass and there 

 consumes the acid which has been produced by the lactic acid 

 bacteria and is retarding the development of the albumin-degrad- 

 ing organisms. The favourable influence of this thread fungus is 

 so indubitably established by experience, that the practice is now 

 common to sow it purposely in the fresh cheese mass. To this 

 end bread is allowed to become covered with a luxuriant growth 

 of mould, and is then dried and ground, the resulting powder 

 (rich in mould spores) being then strewn between the separate 

 layers of the sliced curd. In order to favour the development of 

 VOL. i. x 



