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Bacteria of normal and almormal milk, L. Adametz {JVoa. 1-3, Oesfer- 

 reieh. MonatsHch.J'ilr Thierheilhunde,'lHiH)). — This is a review of our pres- 

 ent knO\vleil<;e in regard to bacteria in milk. The autlior first points out 

 that since milk is free from bacteria when drawn from the cow the num- 

 ber i>respnt in milk wliich is immediately consumed is likely to be so 

 small as to render them of no significance. But when milk is allowed 

 to stand for a while before being used the bacteria increase marvelously. 

 In such milk there is a great variety of bacteria, which produce changes 

 resulting in various forms of abnormal milk. JS^ormal milk, according 

 to Adametz, has the following characters: wlien freshly milked it has a 

 characteristic taste and odor and an amphoteric reaction; it is readily 

 coagulated by rennet, and if left to itself will become acid after from 2 

 to 4 days, and will eventually curdle. Any milk which shows other 

 characters than these is regarded as abnormal milk. 



Four different ways in which milk curdles abnormally are distin- 

 guished as follows: (1) The casein becomes jelly-like and a layer of 

 cloudy liijuid soon appears between the curd and the surface layer of 

 cream. The casein soon dissolves and the liquid increases. (2) The 

 casein is precipitated as a compact mass with a little cloudy liquid 

 between the curd and the cream. (3) The casein becomes flaky and 

 collects at the bottom of the vessel in which it is contained. It soon 

 becomes more or less dissolved into a liquid. (4,) A fermentation 

 appears at the same time with the curdling, which breaks up the curd 

 ami causes a mixing of the ingredients of the milk so that there is 

 formed a compact, fermented mass containiug much fat, while a clear 

 liquid appears at the bottom of the vessel. 



The bacteria which are commonly found in milk are divided by the 

 author into two classes, according to their effects. One class changes 

 the milk sugar into lactic acid, which soon curdles the milk. The typi- 

 cal si)ecies of this class is one commoidy known as the sour milk ba- 

 cillus {Bacillus acidi laetici). This is certainly a common form, although 

 many other species of b.icteria have the same effect, even some of the 

 pathogenic bacteria thus producing lactic acid. The second class pro- 

 duces a curdling of the milk by the formation of rennet-like ferment, 

 and the curdling of the milk is soon followed by a solution of the curd. 

 Bacteria of this class render the milk slightly alkaline or do not affect 

 its reaction. This class comprises a large number of species, most of 

 which have the further character of liquefying gelatine. Many of them 

 produce spores which resist a high heat. The fermentations which 

 occur in boiled milk are usually caused by bacteria of this class, since 

 the boiling kills all of the acid-forming species. They produce a marked 

 decomposition of milk, giving rise to peptones, leucin,tyrosin, and many 

 other products. There seem to be two distinct ferments (enzymes) pro- 

 duced by these bacteria; one, like rennet, curdles the milk, and the other, 

 like try|)sin, has the power of peptonizing the casein. Ordinarily their 

 presence in milk is so disguised by the acid-forming species that they 



