CONTAGIOUS DISEASES OF DOMESTICATED ANIMALS. 475 



a matter of extreme difficulty to account for tlie cause of an outl)rcak of 

 the plague. 



Tiie vitality of tlie contagious matter is variable, according to circum- 

 stances. Air is its most potent and reliable destroyer. Hay and straw 

 wliicli bave lain above the stables of sick animals have been often used 

 as fodder with impunity after an airing of t\jenty-four hours. Wool, 

 impregnated with the mucus from the nostrils of sick animals, was found 

 to ]ie innocuous when thoroughly aired for five or six days. Stables 

 and pasture-grounds will be tlioroughly disinfected in a few weeks by 

 the action of the atmosphere. In the same way clothing and other po- 

 rous substances become entirely disinfected by airing. The stronger the 

 current of air the more prompt its disinfecting action. On the contrary, 

 if infected porous substances are not exposed to currents of air, the con- 

 tagious matter is preserved for a long time. Closely-packed hay and 

 straw, the woodwork and floors of closed stables, manure-heaps, packed- 

 up clothing, &c., may remain infected for several months. A case is re- 

 corded of the rinderpest breaking out anew in a stable which had stood 

 empty for four months, but had not been disinfected after a previous 

 outbrealj. The flesh and hides of carcasses which had been buried for 

 over three months were found to be capable of infecting healthy an- 

 imals. 



Very high temperature has the same effect in destroying the power 

 of the contagious matter as currents of air, but summer heat is effective 

 only in so far as it promotes the drying up of the contagious particles, 

 and renders them more volatile and more easily diluted by the air. 



Tlie contagious matter is not destroyed by cold, not even by frost ; 

 on the contrary, its power is preserved, as the drying up of the sub- 

 stances containing it is thereby hindered. Dung frozen through the 

 winter spreads the contagion upon thawing in the spring. 



All ruminating animals are liable to the rindei-pest, but goats and 

 sheep are less commonly and less severely affected by it than neat cat- 

 tle. The disease does not afl'ect non-ruminating animals, nor is it in any 

 way dangerous to man. 



The rinderpest breaks out generally on the fifth or sixth day from the 

 time of infection, sometimes as early as the fourth, and irequently as late 

 as the eighth or even ninth day. According to some observations, the 

 period of incubation may extend to two or three weeks, but the instances 

 of so protracted an incubation are to be considered as entirely excep- 

 tional. 



The spread of the disease in a herd of 'cattle is usually slow in the 

 beginning. Often when the contagion is introduced only a single ani- 

 mal is infected. This one, after the few days required for the incuba- 

 tion, becomes sick and commences to evolve the contagious matter, 

 which ir;fGCus one or more of the animals in the same stable or herd. 

 Then, again, an interval of time elapses before the disease is developed 

 in the new victiins. As soon as several animals are diseased, the con- 

 tagion spreads more rapidly, and many are attacked at the same time. 

 Want of proper caution on the part of stable-men and other attendants 

 is often tiic cause of an exceedingly rapid progiess of the contagion, 

 which is carried in their clothing from one end of the stable to another. 



PIIEN03rE]?rA OF CATTLE PI^AGLTE DURING LIFE. 



Dr. J. Eurdon- Sanderson, one of the commissioners appointed by the 

 English Goveniment to investigate this disease during its last invasion 

 of \Vestern Europe (1865), in speaking of the i^henomena of cattle plague 



