lio. 480] EXTINCTION OF MAMMALIA 



835 



Tupeds (compare Gregory, p. 266). It is fatal to the following 

 forms: wild buffalo, Bos (Bubalus), the kudu {Sirepsiceros kudu), 

 the sable antelope (Hippotragus niger), the gnu {Connochoetes 

 ■alhojvbatv^ and C. taurina), also in the Philippines to the carabao 

 {Bos (Bubalus) kerahau). It is fatal to from 90 to 100% of domes- 

 ticated cattle. Unlike the diseases before considered: (1) the 

 parasite causing rinderpest is undiscovered, (2) no natural im- 

 munity is known (methods of artificial immunity were discovered 

 in 1893), (3) it is distinguished by the ease and rapidity with which 

 it spreads in all countries, climates, and seasons, being carried 

 •even on the clothes and person of man. It therefore appears 

 improbable (Bruce) that insects have anything to do with it. It 

 may be due to a wind-borne bacterial organism. 



This disease has been known from time immemorial in Europe 

 and Central Asia. It is believed by some to have entered the Nile 

 provinces of 1880, to have reached the Transvaal in 1896, and thus 

 to have traveled the whole length of Africa in fifteen years. The 

 spread in Africa has been largely through the wild ruminants. 



By analonv we can imagine that a disease affecting the Pleisto- 

 cene horses of Xorih America may have traveled an equal distance, 

 namely, from Texas to Patagonia, and destroyed all the South 

 American K(|iii(Ia'. 



Local Dislrihufion, Jninnnnf;/. llnrsr SIr/rnrs, — A very impor- 



its distribution, prevailing in low countries and during wet sea- 

 sons. The infection is not carried into the high country or dur- 

 ing the dry season.^ The parasite causing it is unknown, and is 

 believed to be ultra-microscopic. It is believed to be carried in 

 the blood because the 1,000th part of a single drop of blood injected 

 under the skin of a healthy animal will cause death; some horses 

 require a larger dose than others, indicating fluctuations in power 

 of resistance or immunity. Unlike the foregoing diseases it is not 



goats, and sheep (Bovidse), which is similar in distribution to the heart-water 

 horse sickness and is carried by the bont-tick (Amblyom?na hehrceum), in that 

 it dies out on the high veldt. Similarly again the catarrhal fever of sheep has 

 a distribution in South Africa similar to that of horse sickness, and is probably 

 -carried by means of the same night-feeding insect. 



