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THE AMERICAN NATURALIST [Vol. XL 



beests, blesbucks, and spring-bucks, with their bodies covered 

 with this disease. I have known seasons when the three latter 

 animals were so generally affected by it, that the vast plains through- 

 out which they are found were covered with hundreds of skulls 

 and skeletons of those that had died therefrom." 



Aflalo ^ in his paper "The Beasts that Perish," has discussed 

 many of the various causes of extermination and gives disease a 

 prominent place. Among the Carnivora there are the non-epi- 

 demic diseases, such as distemper, affecting dogs, foxes, wolves, 

 cats, and other wild felines. The more rare and sporadic 

 epidemics claim victims among the Carnivora wholesale. The 

 prevalence of rabies among foxes was observed on the continent 

 from 1830 to 1838 in Switzerland, also in Wurttemberg and 



Carnivora are protected by their relatively non-gregarious 

 habits. On the contrary^ the more gregarious Herbivora offer 

 much more favorable conditions for the spread of disease. Flem- 

 ming in his Animal Plagues enumerates 86 epidemics affecting 

 wild quadrupeds and birds. In the list are diseases affecting 

 nearly every wild species in Europe and some in the New World, 

 including the red deer {Cervus elaphus), reindeer (Rangifer fa- 

 randus), the chamois (Rupicapra tragus), wild hog, also among 

 the Carnivora, wolves, foxes, bears, among the Rodentia, the hares, 

 rabbits, and rats. Various forms of tuberculosis account for a. 

 large percentage of death among domesticated animals. Only 

 the goat enjoys immunity from it. Among animal plagues anthrax 

 was formerly the most rapid and deadly, and is now perhaps the 



gists are familiar wit It tlie spread of disease from domesticated 

 to non-domesti( iit('(l animals, of the sheep scab, for instance, to 

 the wild sheep (Ocl.s montana). 



Insects and Injection.— In my opinion the most striking advance 

 toward a complete theory of the causes of natural extinction has 

 come from recent discoveries regarding the real nature of the 

 animal diseases and how they are communicated. Only recently 

 have we come thoroughly to understand that insects are the most 



