BACTERIA IN THE INDUSTRIES. lOI 



cheese with pure ciiltures of the kind of microbe producing the desired flavor 

 as Roquefort, Bre, Limburger, etc. In time it wUl no doubt be possible to 

 produce hitherto unheard-of cheese flavors by means of new species, varieties, 

 and strains of cheese microbes. Cream- and butter-flavor bacteria are also 

 used. The souring of milk is due to the omnipresent but Uly defined Bacillus 

 acidi lactici and other bacteria. Stringy or ropy milk is due to bacterial in- 

 fection. Under conditions favorable to the development of the organisms, 

 the ropiness appears within from twelve to twenty-four hours after milking, 

 and becomes so pronounced that the milk can be drawn out in long threads 

 or strings. It is a not uncommon condition of milk in Switzerland, where it 

 is considered specially noxious, but in Holland it has been produced by 

 design for making Edam cheese. Ropiness of milk is caused by a variety of 

 micro-organisms, among them being Bacillus actinobacter, B. lactis viscosus, 

 B. gummosus, etc. The micro-organism used in Holland for the manufacture 

 of the cheese referred to is known as the Streptococcus hollandicus. The 

 Bacillus cyanogenus causes the milk to become blue without coagulating it or 

 rendering it acid. The Bacillus butyricus occurs in milk which it coagulates, 

 also producing butyric acid. It is this microbe which develops the rancidity 

 of butter. There are, however, many different species of microbes which 

 produce butyric acid fermentation. 



Freshly drawn milk is not germ-free, even under the most aseptic and sani- 

 tary conditions and surroundings. As a rule even the milk in the udder con- 

 tains some germs, in spite of the fact that rrulk possesses decidedly bacteri- 

 cidal properties. However, the milk from different animals varies in this re- 

 gard. The bacterial impurities of freshly drawn mUk are traceable to the 

 skin of the cow, the dust and filth about cow stables, the vessel containing 

 the milk, and above all to the hands of the milkers. The milker is often 

 the cause of inoculating the milk with disease germs, as typhoid, colon 

 bacillus, diphtheria, scarlet fever, small-pox, and tuberculosis. The medical 

 journals cite cases of typhoid epidemics traceable to mUkers who were "ty- 

 phoid carriers" without actually suffering from the disease. Cows are very 

 susceptible to tuberculosis, and the milk from tuberculous animals has in- 

 fected thousands upon thousands of children and many adults. 



Since milk is an excellent culture medium for a great variety of germs, it 

 is evident that, under favorable conditions, it may be a fruitful source of 

 infections. Serious epidemics of t3rphoid fever and of diphtheria have 

 been traceable to and exactly limited to the mUk route of a certain dairy- man. 

 Tuberculous infections of the children in a number of families have been 

 traceable to the milk from a single animal. As a rule mixed milk (that is the 

 milk from many animals) is safer than the milk from a single animal, though 

 this is not necessarily always the case. The milk from animals that are free 

 from disease and that are tested regularly (every six months) for tuberculosis, 



