DISEASES OF SWINE AND OTHER ANIMALS. 99 



> 

 the. Eun at mid-dav may suffice to set the vims free. Again, wjiile tliey are especially 

 (laugeror.s on thc'^ accession of v/armer weather, yet, when once the tcmperatiire has 

 risen pernianoiitly above the freezing point, wo may count upon the rapid putrefaction 

 that ensues in all organic bodies that have been fi'ozen and on a disiufection almost aa 

 speedy, cud it maybe at times even more speedy than in thq extreme heat of summer. 

 The course of safety is to hold all places that have been infected in late autumn or 

 during Avinter as still infected until one or two months after the frost lias gone out of 

 tlie ground in spring. 



This, of corj;x', lias little bearing upon tho question of covered pens, bams, cars, &c., 

 in which the poison may bo preserved dry, active, and accessible in winter andsmmner 

 alike. On this question of infection through pens in winter I instituted the following 

 expcriin'.'ut : 



COXTAGIOX FROM AX INFrXTKD PEN. 



A healthy pig was placed in a pen from which a sick one had been removed thartcen 

 days before. The pen had been swept out, but subjected to no disinfection other than 

 the free circulation of air ; and as the pig Avas placed in tho pen on December 19, all 

 moist objects had been frozen during tho time the apartment had stood empty. The 

 pig died on the fifteenth day vrithout having shov.n any rise of temperature, but with 

 2)0sf morter.i lesions that shoAved 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 tho fuU development of all the other lesions. It sufficiently demonstrates the pres- 

 ervation of the poison in covered huildings at a temperature below the freezing poiut. 



SUCCESSFUL IKOCULATIO:^; OF PIGS WITH VIRUS THAT HAD BEEN KEPT FOR A .AIONTH 



IN DRY WHEAT-BRATS'^. 



Appended will bo found the daily record of two pigs infected by inoculation with 

 bowel ingesta and mucous membrane that had been preserved for a mouth in diy 

 wheat-bran. In both cases tho disease followed the inoculations promptly and ran a 

 severe course, one case jiroving fatal, while in the other death was anticipated by kill- 

 ing the animal. At tho autopsies the usual characteristic lesions were found. 



Here, as in the case of the virus j)reserved on quill-tips, we find the poison pre- 

 served Avithout the slightest impairment of its potency. Thus two series of inocula- 

 tions with di'ied Aarus show hoAS' careful aud thorough must be the disinfection in dry 

 seasons, and indoors in all seasons, and the importance of the destruction by tiro, or 

 in other certaiu manner, of all diy fodder and litter in Avhich tho poison may have 

 been secreted. 



COHABITATION WITH SICK TIGS IN DIFFERENT STAGES OF TIIK DISEASE. 



A healthy pig was inclosed in a pen Avith a sick one which had I'een inoculated with 

 virulent blood on tAvo occasions ; the first thirty days and tlie last five days before. 

 After the first inoculation the pig had suficred from a slight fcA'cr and Ihe charactfristio 

 phenomena of the tlisease. Before the second inoculation the temperature had been 

 normal for eight days, and it was not materially affected by the operation. In short, 

 the disease had manifestly spent itself in the system of ili« pig, though it had left it 

 a most shrunken, emaciated, and Avretched spectacle. 



The tAvo ]iigs occupied the same pen, lay on the same hed, and fed from the same 

 trough for sixteen days, during Avhicli no uueijuivocal sign of disease Avas mauitested 

 in the healthy jiig. It seemed indeed to have suecessfuliy resisted the, contagion. 



It Avas noAV removed to another ]k'u and placed in CGm]»any AvLtli a i)ig in Avhich the 

 disease had j'ust reached its height. On the tAvelfth day tliereaftfu' its temperature 

 permanently rosc^, and it passed through a sharp attack from whicli it is now rocover- 

 ing. 



This seems to show that the poison is much less virulent after tho febrile stage of 

 the malady has passed, and that tho danger from the recuperating animal decrtnisea 

 with advancing convalcsceuce. At the same time it must not be too hastily conclnded 

 that a mild form of the disease did not exist in tbis pig during tho occui»aucy of ilio 

 first pen. It ap])ears uiujuestionable that the poison may bo prosont in thosy^tiMu, 

 and yet give rise to so little disorder tliat the most careful observer wouhl fail to 

 detect anything anuss. 



OCCUr.T FOKAIS OI.' TIIK DISKASK. 



On posl-morlcm sections I haA'o found the eharacieristic lesions of Iholtowels and 

 lymphatic glands, in cases where no uutaneon.-i rash or discolor;! I io:\, no lisc of tem- 

 perature, no loathing of food, nor constitutional disiu'dcr had bt'traycd its presence 

 dm'iug life. The occuvrcnce of such slight aud occult forms of the disease must present 



