The Cattle-Plague. 253 



writing to Lord Clarendon from Warsaw, in 1857, attril:)utes tlio 

 difference to the superior constitutional strength of the aboriginal 

 race of Polish cattle. Without denying this fact, it is necessary 

 to bear in mind that we are led by due observation of small-pox 

 to expect such behaviour, which, as Dr. Playfair observes, 

 although fatal enough with us, acts as a most malignant pest when 

 it deserts its usual haunts. It is hopefully characteristic of this 

 poison that it requires the presence of certain congenial condi- 

 tions — perhaps of the climate, perhaps of the animal organism ; 

 certainly of the latter, for the deteriorated animals always first 

 fall victims, and then, as the virus strengthens, the rest are carried 

 off". Pi'ofessor RoLL has found this to be the case in Austria. 

 He says the cases are sporadic in certain years, and that it only 

 becomes generally diff'used in years when contagious diseases 

 among men show a severe type. Without this ray of hope we 

 might well view with dismay the growing demand for foreign 

 cattle, and the vehicular facilities devised for the enlarged pro- 

 portions of this trade. 



Cause. — Having already trenched upon this subject in the 

 section accorded to Origin, I intend to deal briefly with it in 

 order to allow the more room for what naturally follows. 



It is generally allowed that disease is referable to two causes 

 — existing and predisposing. With the desire to be rather more 

 definite, some authorities acknowledge a third set of causes, 

 which they term exciting. In order to set up a disease, the 

 existing and predisposing causes must be present. The existing 

 tendency to death is ever present in the organism, which is born 

 to die — not so the predisposing. Among the latter may be 

 enumerated hereditary tendency ; a plethoric state of body 

 induced by high living and little exercise ; a deteriorated state 

 of body induced by low living and impure air ; a depressed 

 circulation and susceptible nervous system ; previous disease ; 

 mechanical and chemical injuries; atmospherical changes and 

 conditions — extreme heat, extreme cold, excessive moisture, 

 excessive dryness, different electrical conditions, variations of 

 the barometer, and paucity of light. Further, the atmosphere, 

 and it may be added the water, contain impurities that have the 

 power of exciting disease : these are, the matter of malaria, in- 

 ducing ague ; contagion, causing various fevers, «Scc. ; and 

 noxious gases. 



Dr. Brocklesby (1746), who minutely studied the charac- 

 teristics and causes of the plague that attacks the human 

 organism, compared the zymotic germ of that disease to an 

 exotic, which, being transplanted from its locus natalis in other 

 other lands, exists here for a time, and then dies out. It is a 

 question whether we must not adopt the same view : for although 



