OHAP. vr. MICRO-ORGANISMS IN THE RIPENING OF CHEESE. 343 



the growth of the characteristic moulds. Every one knows the diffi- 

 culty of starting Stilton cheese-making in a dairy in which it has not 

 been made before, and which is not in a Stilton district. The process 

 of manipulation may be properly learned, and faithfully imitated, and 

 3 r et the desired flavour is not obtained. The cheese may be rich and 

 good, but it is not ' real /Stilton.' Instances, however, can be now 

 pointed to in which after? previous failure the would-be Stilton-maker 

 has succeeded by adopting the scientific process of inoculating his curd 

 with fragments of well-ripened Stilton cheese of first rate quality from 

 a good Stilton dairy, with the ultimate result that the necessary 

 organisms have been acclimatised in their new home, and the making 

 of Stilton has become a pronounced success. The very atmosphere of 

 an old dairy is probably thronged with the germs of the organisms, 

 that have long been at work, hourly and daily, and yearly, in its 

 ripening-room. Many of these oi'ganisms have been individually 

 studied by biologists abroad, though little scientific work has been 

 directed to them here, and the sum total of the knowledge yet 

 gained about them is very small. But the mere discovery of the 

 principle that specific ripening is caused by specific organisms work- 

 ing under specific conditions, apart from a knowledge of individual 

 species themselves, has already produced such practical results as 

 these. 



" The recognition of th fact that we depend on micro-organisms for 

 the conversion of curd into cheese, and of the further fact that the 

 culture of these organisms is greatly under our own control, at once 

 imparts to the empirical processes of cheese-making an interest which 

 to the intelligent dairy farmer they never previously possessed. It 

 throws a new light upon his operations, and awakens observations 

 and a desire for experiment in a far more systematic fashion than was 

 formerly possible, and it is probable that in another half century 

 practical cheese-making will be as much controlled by scientific 

 principles as is already the case in brewing, a process in which the 

 study of micro-organisms and their effect has assumed a great regu- 

 lating influence. 



" To illustrate how close is the correspondence between science and 

 practice in some methods of cheese-making, we may briefly compare 

 two different methods practised in Cheshire, viz., the production of 

 old-fashioned late-ripening cheese, and that of the more modern early- 

 ripening cheese. We will then see how the results arrived at in 

 practice correspond with those which we should theoretically expect to 

 happen from what is known of the genei'al properties of organized 

 ferments and of their work in producing organic changes more or 

 less rapid for the ripening of cheese is, as already said, essentially 

 a series of organic changes wrought by living organisms. In a 

 dairy in which old-fashioned late-ripening cheese is made, the greatest 

 care is taken to strain and rapidly cool the evening milk, to keep 

 it cool all night, and even to keep it covered till morning. The rennet 

 is so proportioned as to produce a curd that will separate cleanly and 

 firmly from the whey, very little acidity is allowed to develop, and 



