408 REPORT OF THE COMMISSIONER OF AGRICULTURE. 
the sun at mid-day may suffice to set the virus free. Again, while they are especially © 
dangerous on the accession of warmer weather, yet, when once the temperature has 
risen permanently above the freezing point, we may count upon the rapid putrefaction 
that ensues in all organic bodies that have been frozen and on a disinfection almost as 
speedy, and it may be at times even more speedy than in the extreme heat of summer. 
The course of safety is to hold all places that have been infected in late autumn or 
during winter as still infected until one or two months after the frost has gone out of 
the ground in spring. 
This, of course, has little bearing upon the question of covered pens, barns, cars, &c., 
in which the poison may be preserved ary, active, and accessible in winter and summer 
alike. On this question of infection through pens in winter I instituted the following ~ 
experiment: 
CONTAGION FROM AN INFECTED PEN. 
A healthy pig was placed in a pen from which a sick one had been removed thirteen 
days before. The pen had been swept out, but subjected to no disinfection other than 
the free circulation of air; and as the pig was placed in the pen on December 19, all 
moist objects had been frozen during the time the apartment had stood empty. The 
pig died on the fifteenth day without having shown any rise of temperature, but with 
post mortem lesions that showed the operation of the poison. This case was an exam- 
ple of the rapidly fatal action of the disease, the poison having fallen with prostrating 
effect on vital organs—the lungs and brain—and cut life short before there was time 
for the full development of all the other lesions, It sufficiently demonstrates the pres- 
ervation of the poison in covered buildings at a temperature below the freezing point. 
SUCCESSFUL INOCULATION OF PIGS WITH VIRUS THAT HAD BEEN KEPT FOR A MONTH 
IN DRY WHEAT-BRAN,. 
Appended will be found the daily record of two pigs infected by inoculation with 
bowel ingesta and mucous membrane that had been preserved for a month in dry 
wheat-bran. In both cases the disease followed the inoculations promptly and ran a 
severe course, one case proving fatal, while in the other death was anticipated by kill- 
ing the animal. At the autopsies the usual characteristic lesions were found. 
Here, as in the case of the virus preserved on quill-tips, we find the poison pre- 
served without the slightest impairment of its potency. ‘Thus two series of inocula- 
tions with dried virus show how careful and thorough must be the disinfection in dry 
seasons, and indoors in all seasons, and the importance of the destruction by fire, or 
in other certain manner, of all dry fodder and litter in which the poison may have 
been secreted. 
COHABITATION WITH SICK PIGS IN DIFFERENT STAGES OF THE DISEASE. 
A healthy pig was inclesed in a pen with a sick one which had been inoculated with 
virulent blood on two occasions; the first thirty days and the last five days before. 
After the first inoculation the pig had sufiered from a slight fever and the characteristic 
phenomena of the disease. Before the second inoculation the temperature had been 
normal for eight days, and it was not materially affeeted by the operation. In short, 
the disease had manifestly spent itself in the system of the pig, though it had left it 
a most shrunken, emaciated, and wretched spectacle. 
The two pigs occupied the same pen, lay on the same bed, and fed from the same 
trough for sixteen days, during which no unequivocal sign of disease was manifested 
in the healthy pig. It seemed indeed to have successfully resisted the contagion. 
It was now remoyed to another pen and placed in company with a pig in which the 
disease had just reached its height. On the twelfth day thereafter its temperature 
permanently rose, and it passed through a sharp attack from which it is now recoyer- 
ing. 
This seems to show that the poison is much less virulent after the febrile stage of 
the malady has passed, and that the danger from the recuperating animal decreases 
with advancing convalescence. At the same time it must not be too hastily concluded 
that a mild form of the disease did not exist in this pig during the oceupancy of the 
first pen. It appears unquestionable that the poison may be present in the system, 
and yet give rise to so little disorder that the most careful observer would fail to 
detect anything amiss. 
OCCULT FORMS OF THI DISEASE. 
On post-mortem sections I have found the characteristic lesions of the bowels and 
lymphatic glands, in cases where no cutaneous rash or discoloration, no rise of tem- 
perature, no loathing of food, nor constitutional disorder had betrayed its presence 
during life. The occurrence of such slight and occult forms of the disease must present 
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