808 
W. L. WILLIAMS. 
in which case the larger the volume of milk retained in a body 
the greater the source of danger, and we find this borne out 
again by our observations that animals having commodious 
milk cisterns like the cow, goat, and ewe suffer most frequently 
and acutely from mastitis, although otherwise more immune 
against wound infection than some other animals. Franck has 
also pointed out that in udders possessing milk cisterns the 
infection is general in that division of the gland emptying into 
the infected cistern, so that in the cow usually an entire quarter 
is infected, while in carnivora the infection may be limited to a 
lobule of the gland. Udders without milk cisterns are notably 
vulnerable to carcinoma, sarcoma and actinomycosis, thus sug¬ 
gesting that a large quantity of milk in a cistern where it plays 
the part of a foreign body in relation to infection invites acute 
purulent disease, while in the absence of this the more chronic 
and permanent infections are liable to occur. 
The method of infection may vary, and as Vennerholm 
(Bayer and Frohner’s Handbuch, B. II., Theil III.) and others 
hold, may be through the medium of the blood or lymph stream 
or through the teat orifice. The infection of the uddtr by means 
of the blood or lymph stream, like in ordinary wound infections, 
speaking from a clinical standpoint, is well-nigh unknown, ex¬ 
cept perhaps tubercular mastitis, and we shall therefore not 
consider this phase of the question further. 
As in ordinary wounds the infection occurs almost always by 
methods readily understood-, through the teat orifice, which from 
our point of view represents the wound opening. Aside from 
the predisposition to mastitis owing to extreme development of 
the milk^ glands and the presence of a milk cistern, we should 
expect, and do find, the affection most common in those animals 
the teats of which most frequently come in contact with putre¬ 
factive substances, such as rapidly decomposing excreta, re¬ 
tained placenta and the like, and these conditions are best filled 
by ruminants, the prominent inguinal udder with its long teats 
being unusually exposed to contact with infective material 
while the animal is recumbent, the long teats being compressed, 
