100 PRINCIPLES AND PRACTICE OF MILK HYGIENE 
but it is occasionally enzodtic, especially when musty 
or mouldy straw is used for bedding. It is most fre- 
quently seen in fresh cows, after they have been put on 
full feed, and it is probably for this reason that the fu- 
runcles are spoken of as feed boils. Firm, painful, nodu- 
lar swellings, varying in size from a pea to a walnut, 
appear in the subcutaneous tissue of the udder. In 
seven or eight days a dark area of puriform softening 
develops in the centre of each individual swelling, which 
subsequently ruptures at this point and discharges its 
contents of pus mixed with shreds of tissue. This dark 
patch, or the scab of dried blood which subsequently 
forms at the point of rupture, has given the process the 
popular name of black scab in some sections. The milk 
secretion is not affected, but the milk may be contami- 
nated secondarily with the purulent discharge. 
ANTHRAX 
The question of using the milk from a cow affected 
with anthrax does not often arise in practice because, 
as a rule, the milk secretion ceases suddenly with the onset 
of the fever, while in those cases in which it continues 
it is reduced to a small quantity and is very much changed 
in appearance. It is more yellowish than normal, slimy, 
sometimes bloody, with a bitter taste, and after standing 
undisturbed for a few hours separates into alayer of cream 
and of serum. Anthrax bacilli are excreted through the 
udder only in the advanced stages of the disease, after they 
have invaded the blood stream and when the udder is 
affected. But the chances of milk becoming infected 
secondarily are very great. The bloody discharges and 
the manure from infected animals contain the anthrax 
