MICROBES IN CHEESE-MAKING. 153 



salting, oiling and rubbing the surface. But bacteria appears to have, 

 if not the chief share, certainly a large share in the production of the 

 flavors. Experiment has shown that bacteria grow abundantly in the 

 cheese during the ripening; that some species of bacteria can produce in 

 milk flavors similar to those found in the ripened cheese; that treat- 

 ment which prevents the growth of bacteria prevents also the develop- 

 ment of the flavors in the cheese. Further, in the manufacture of the 

 famous Holland cheese (Edam cheese), the cheese-makers have learned 

 fliat by planting certain species of bacteria in the milk out of which 

 the cheese is to be made, the ripening may be hastened and made more 

 uniform. In Holland about one third of the cheese is made by thus 

 inoculating the milk with 'slimy whey,' which is simply a mass of whey 

 containing in great numbers certain species of bacteria. These facts 

 indicate strongly that the bacteria are agents in this flavor production. 

 But, at the same time, the subject has proved so difficult of investiga- 

 tion that our bacteriologists are as yet by no means satisfied with the 

 results. Indeed, they differ very decidedly in their conclusions. Some 

 believe that the ripening is chiefly due to the same class of bacteria 

 which produce the souring of milk; others think it due to bacteria which 

 produce an alkaline rather than acid reaction; some believe it to be a 

 combination of the two, while others, again, decide that cheese ripen- 

 ing is a long process, involving the action of many species of bacteria 

 and perhaps of molds as well. The difficulty lies in the fact that, 

 since the ripening is a long process, many species of bacteria are 

 found in the cheese at different times. This makes it almost impos- 

 sible to determine what is the cause of the ripening and what is only 

 incidental. 



It will be readily understood that the problem of cheese ripening is 

 one most eagerly studied by bacteriologists. The immense financial in- 

 terests involved in the discovery of definite methods of handling the 

 manufacture and the ripening of cheese would insure this, entirely inde- 

 pendently of any scientific interest. A very large per cent, of cheeses are 

 ruined by improper ripening, and the discovery of methods for prevent- 

 ing this loss would mean the saving of millions of dollars annually. 

 Moreover, many favorite cheeses have hitherto been capable of manu- 

 facture only in certain localities, probably because these localities are 

 filled with the peculiar species of micro-organisms needed for their 

 ripening. If it were possible to cultivate the requisite organisms and 

 use them for artificial inoculation, it might be possible to manufacture 

 any type of cheese anywhere. Already it has been found that new 

 cheese factories may sometimes be stocked with the proper micro- 

 organisms by rubbing the shelves and vessels with fresh cheeses imported 

 from localities where the desired variety is nominally made. It is 

 evident that immense financial interests may be involved in the proper 



