120 DEPARTMENT OF AGRICULTURE. 



Texas is concerned, I have satisfied myself that the disease is universally prevalent in 

 that State. 



Its complete manifestation is readily witnessed in States north of 34 north latitude. 

 Here the malady can no longer be declared indigenous ; but there are numerous instances 

 which can be cited of purely enzootic diseases spreading a certain distance by contagion. 

 Two of the most marked instances arc furnished us by the malignant anthrax of Russia, 

 better known as the Siberian boil plague, and the milk-sickness, or trembles, of the United 

 States. 



The milk-sickness is due to cattle feeding on low woodland pastures, where certain 

 poisonous plants abound. It originates only in a very limited area of country; but the 

 animals may travel, and their flesh and milk will communicate the disease when eaten 

 by other animals, and even by human beings. Trembles is, therefore, an enzootic disorder, 

 capable of being primarily produced only in definite localities; but the poison which con 

 taminates the food is capable, through that food, of attacking a second and a third 

 animal, or as many as partake of it. There is another striking similarity between the 

 course of milk-sickness and splenic fever. The animal food, poisoned in the disease-pro 

 ducing district, may show no signs of disease, unless subjected to a definite existing cause, 

 such as being driven or frightened. In classifying trembles among the diseases of the 

 lower animals we should undoubtedly place it among the effects of vegetable poisons, and 

 study it as a very remarkable toxicological phenomenon. I should be disposed to deal 

 with splenic fever in the same way. Southern cattle, accustomed to feed on certain pas 

 tures in Florida and Texas, thrive, and their systems become charged with principles 

 which are thrown off in the excretions for many weeks, and probably two or three months 

 after they leave their native soil. Herds of these animals necessarily deposit a large 

 amount of whatever they excrete ; and thus pastures are contaminated, the grasses of 

 which prove deadly poisons to healthy and susceptible cattle. It is certain that the feeding 

 of cattle on the land over which Texan animals have passed is the ordinary, and probably 

 invariable, cause of splenic fever. 



The circumstances under which the disease manifests itself tend to favor the view 

 that it is allied to the numerous forms of anthrax fever which prevail very generally in 

 hot countries, and usually in low lands. These diseases, it is true, are scattered through 

 out the temperate /.one; but their development depends upon heat, wherever it appears on 

 stiff, retentive soils, and in some sandy but fertile lands their ravages are especially wit 

 nessed during w r et seasons. Heat favors and creates the manifestations of splenic fever. 

 The malady springs in a warm country, and is propagated most readily with heat and 

 drought. It is indigenous where vegetation is rank, and the soil is charged with an excess 

 of organic life, which, for want of direction, tends to waste and mischief. During the 

 hot summer months anthrax or carbuncular fevers force the stock-owners of Southern 

 Europe to seek the hills with their-flocks of sheep and goats; and to disregard this injunc 

 tion involves, not onlv the death of their animals, but the destruction of other warm-blooded 



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creatures, including man himself, by malignant pustule. To this category undoubtedly 

 belonged the various pests of old; and, by traveling northward, the virulence of these 

 diseases, the development of the anthrax poison, and the propagation, under any circum 

 stances, by contagion, diminish by simple and imperceptible gradations, and ultimately 

 cease. The black-water of Great Britain and of America is one of the forms of this 

 deadly anthrax, which, even so far north as Aberdeen, in Scotland, has been communi- 



