78.2 OBSERVATIONS ON THE LUNG PLAGUE OF CATTLE. 
recovery. The imprisoned mass of dead lung completely ex¬ 
cluded from contact with air and aerial germs does not putrefy, 
and never exhales a septic odour. It undergoes a slow meta¬ 
morphosis through its contained cells and granules into a puru¬ 
lent liquid, which is observed with equal tardiness. The lique- 
factive metamorphosis commences at the surface, separating the 
dead mass from the sac, so that it appears for the future as a 
great solid nucleus floating in a variable amount of purulent fluid. 
When large masses are encysted in this way it may be over a 
year before the whole has been liquefied and removed, and not 
unfrequently after nine months the outline of lobules, air-tubes, 
blood-vessels, and nerves can still be traced with ease in the 
necrosed lung. 
The important bearing of this is related to the lack of all 
putrefaction or other important changes in the mass of necrosed 
lung, which, in the absence of such metamorphosis, remains an 
encysted mass of infecting material so long as it continues solid 
and unchanged. To the average mind, and even to the medical 
one who has made no special study of this disease, the danger 
even of infection seems past when the patient has for some time 
resumed its appetite, rumination, milking, natural breathing, 
and, above all, its disposition to lay on fat. Yet the majority 
of patients that have apparently recovered, carry within their 
chests the encysted necrosed masses above described; and so 
long as these remain they cannot be considered otherwise than 
as exceedingly dangerous to other stock. It is true that the 
bearers of these encysted masses will often stand for months 
beside other cattle without infecting them, but it is none the 
less true that each bears within its chest a sealed up store of 
infection, and there is only wanted a breach or change in the 
surrounding fibrous envelope to allow the deadly virus to escape. 
Instances of Infection from Encysted Necrosed Lung .—Charles 
Beeves, Success, Suffolk Co., N. Y., bought two calves from the 
infected Isaac Billard herd about January, 1879. They did 
badly. In June he lost several animals infected from these, and 
on July 19th I visited his place and found a cow, steer, and a 
calf, infected from the same source. 
George Patrick, Patterson, Putnam Co., purchased a cow in 
Pebruary, 1879, which sickened in April, but recovered. Others 
died in June, July, and August. On September 15th I found 
four sick and had them disposed of; and Oct. 15th, when the 
whole herd was slaughtered, the cow that had recovered in April 
was found to carry still a solid encysted mass as large as an egg. 
This is more interesting as showing the long retention of the 
encapsuled mass, even after a very mild case, than as positive 
proof of the infection from this source. 
