36 DEPAKTMENT OF AGRICULTURE. 



are landed invariably sound in their Innft-s in Liverpool or London. Dan- 

 ish cattle cross the German Ocean and suifer much ill-treatment, but 

 their dissection reveals at no time the lesions of the lung plaj^ue. 



Kot so with Dutch or Irish cattle. They make a short sea voyage 

 from an infected country and propagate pleuro-pneumonia wherever they 

 come in contact with susceptible cattle. 



Innumerable observations undoubtedly shoAV that the lung plague 

 prevails as much, and often more, during hot weather than in the win- 

 ter months ; it spares many cold countries into which it has no oppintu- 

 nity of transportation, and visits the most genial climate whither sick 

 cattle have been taken. Italy and Australia furnish as good fields for 

 its development as the Swiss Alps, and the colder portions of the 

 United States. 



OVERWORK. 



In France and Italy it has been asserted that keeping oxen long in 

 the yoke, exhausting them, starving, and often drenching them with 

 rain, induced the lung disease. I know not what diseases such prac- 

 tices have not been said to cause. If we survey the countries where 

 pleuro-pneumonia has been longest known, and where its ravages have 

 been most intense, we shall find that, as a rule, it prevails among milk 

 cattle that never work, steers that are grazed or stall-fed, and never 

 broken to the plow- or wagon, and herds of breeding stock, as in the 

 Australian runs, never accustomed to restraint or punishment. 



HEREDITARY PREDISPOSITION — CONGENITAL PLEURO-PNEUMONIA. 



It is necessary to establish clearly the difference between hereditary 

 taint and congenital disease. A malady is termed hereditary when it is 

 transmitted from parent to offspring by virtue of a constitutional defect, 

 deformity, or taint. It may, but usually does not, appear at birth. The 

 best example is furnished by cancer, which occurs frequently in the 

 human female, and reciu^s for generations. None of the specific or 

 contagious fevers are hereditary, and although the question has been 

 discussed in relation to pleuro-pneumonia, it can easily be settled. 

 Delafond thought that the deterioration of breeds might favor its devel- 

 opment. And why, then, has the disease not appeared in South America, 

 wiiile it has decimated the matchless herds of England and Aus- 

 tralia? It may be accepted as a settled truth that the lung disease, like 

 the rinderpest and foot and mouth disease, spreads Avithout reference to 

 any ])eculiar breed. Improved and unimproved breeds are alike sus- 

 ceptible of the attection. 



Calves are, however, born at times of sick cows, and present unmis- 

 takable signs of the lung plague. The first observation of this sort was 

 made by llilfcllielscim, in the Ilhine provinces, who dissected the 

 fietuses of cows that aborted under the disease. He found the lesions 



