18 IVIASTITIS OF THE COW 



degenerate, remain and die when the infectious organisms 

 are the stronger. Here a metastatic infectious focus is 

 produced. On the other hand, if the leucocytes are the 

 stronger, the infectious organisms are destroyed without 

 the production of tissue alterations. 



In this manner, as a rule, through infection by the blood 

 to the udder a great number of small foci, distributed 

 throughout the connective-tissue stroma of the udder, are 

 formed. 



Infection of the Udder in General 



The infection of the udder may be divided ^ into milk- 

 infection and stroma-infection, depending upon the posi- 

 tion of the infectious organisms. 



milk-infection [Parenchymatous Mastitis] . 



Definition. — Milk- or parenchyma-infection is an in- 

 fection of the udder in which the bacteria are only found 

 in the milk, or rather in the parenchymatous passages. 



Since the parenchymatous tubular system of one quar- 

 ter does not connect with that of the other quarter the con- 

 dition remains confined to the quarter infected. 



Ports of Infection. — The milk-infection [paren- 

 chymatous mastitis] may be primary or secondary. 



The primary milk-infection is produced by infection 

 through the teat canal or through a ruptured tubule in a 

 fresh wound. 



The secondary milk-infection is a subsequence of 

 stroma-infection [interstitial mastitis] with extension of 

 an infectious focus in the stroma to a milk passage, ulcera- 

 tion through the wall of the tubule and into the milk tubule. 



Milk-infection causes a local condition in the udder as 

 well as general conditions. 



^ I have made this division, since it appears to me better than 

 the old divisions indicated by the position of the disease. 



