Microbie Diseases Individually Considered. 329 



Gangrenous mammitis of milch ewes. 

 This disease, also called mal de pis, araignee, quickly 

 kills ewes which are attacked by it; it is due, accord- 

 ing to the researches of M. J^ocard, to a very fine mi- 

 crococcus, measuring 0-2// in diameter, and associated 

 in groups of four or more, never in chains. It is 

 stained by the method of Gram, is aero-anaerobic, 

 and communicates to bouillon and to milk an acid 

 reaction, coagulating the latter in twenty-four hours. 

 Cultures retain their virulence only when renewed 

 every day. When a culture is inoculated into the 

 teat of a ewe it produces a rapidly fatal mammitis. 

 The goat is refractory. The rabbit contracts an ab- 

 scess from which it quickly recovers. The dog, cat, 

 and guinea pig show only a local oedema. 



Diseases of milk. 



Milk just withdrawn from the udder is free from 

 germs, but after its extraction it may quickly become 

 infected and undergo a series of deteriorating changes. 

 The most important of these deteriorations will here 

 be briefly described. 



Curdled milk. — The curdling of milk results from 

 the lactic fermentation of milk sugar, the acid pro- 

 duced then bringing about the coagulation of the 

 casein. 



The usual cause of this fermentation is the bacte- 

 rium lactis. This is a short, non-motile rod, measur- 

 ing in length 1/i to 8// by 0*6// in thickness, most fre- 

 quently isolated but occasionally arranged in series, 

 and capable of spore formation. 

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