ACUTE INFLAMMATION OF THE UDDER. 
443 
and produce acute mastitis : our knowledge of such conditions is, how¬ 
ever, still very limited, though such irritants are very probably of bac¬ 
terial origin. Frost-bite seldom attacks more than the skin, though it is 
possible the udder may sometimes “catch cold.” As we find in other 
mucous membranes that inflammatory processes are often caused by 
chills, it may possibly be the case in the udder also. 
But more important than any of these are the specific irritants. After 
Franck had directed attention to the point, others described different bac¬ 
teria as the cause of acute inflammatory processes in the udder. The 
number is very large. Some appear to be of a specific nature, others 
produce mastitis when injected into the udder. Of the former may be 
mentioned: Bacterium phlegmasiae uberis (Kitt), Micrococcus mastitidis 
ovis (Nocard), Streptococcus agalactise contagiosa (Nocard, Mollereau, 
Guillebeau, Zschokke), Galactococcus versicolor (Guillebeau), Staphy¬ 
lococcus mastitidis (Guillebeau), Galactococcus fulvus, albus (Guillebeau). 
Many other microbes are capable of producing mastitis if introduced into 
the udder. Such are : the streptococcus of strangles, the pneumococcus, 
the black quarter bacillus, pyogenic cocci, bacillus of malignant oedema, and 
bacteria found in such septic disorders as metritis and omphalitis of foals. 
This diversity in the microbes discovered constitutes no valid objection 
to the parasitic theory; on the contrary, it probably explains the gieat 
variations in intensity, duration, and gravity of the local and general 
symptoms, as well as the disagreement in regard to the efficacy of any 
single line of treatment. Infection may occur by three paths. 
(1) The skin, which, as already remarked, often suffers slight injuries 
sufficient, however, to form the starting-point of infection. M e see, then, 
why cows are more frequently affected with disease of this chaiactei 
than mares, the reason being that their teats are rnoie often injuied 
and simultaneously infected during milking. Disease once pioduced 
spreads, especially in the course of the superficial lymph vessels of the 
udder, and therefore first affects the skin and subcutaneous tissue. 
This method of spread (lymphogenous mastitis, Kitt) is, however, less 
frequent than the next in order, as Johne has shown. 
(2) Infection from the mammary duct. In many cases a drop of milk 
remains hanging at the mouth of the duct, and foims a favouiable culti¬ 
vating medium for pathological bacteria, which pass hence into the 
galactophorous sinus, and finally into the smallest divisions of the 
affected portion of the gland, producing, according to their degree of 
virulence, a more or less violent inflammation of the parenchyma of 
the udder (galactophorous mastitis, Kitt). At the first glance it appears 
astonishing that inflammatory processes aie not moie fiequently pio¬ 
duced in this way. The apparent rarity is explained, however, by the 
fact that an effectual closure mechanism exists in the milk duct, and 
