438 MICROBIOLOGY 



were the first to show that the virus of rinderpest may pass 

 through a filter which arrests the smallest visible bacteria. 

 With a thin walled Berkefeld filter the results vary, the fil- 

 trate sometimes being infective and sometimes the inoculated 

 animals remaining well. The Chamberland F filters kept back 

 the virus. Wooley 13 states that whether or not the virus 

 passes through the pores of a Chamberland depends largely on 

 the condition of the material used in the experiment. Sem- 

 ner 14 found that the filtrate of infective material passed 

 through a Chamberland filter was not virulent. Kolle and 

 Turner 15 obtained similar results. Todd 16 concludes that the 

 filterable nature of the virus is not fully determined. 



Hog cholera. In 1903 de Schweinitz and Dorset 17 found 

 that in certain outbreaks of epizootic hog cholera the blood 

 serum of the diseased hogs when diluted with water and 

 passed through a porcelain filter was still capable of producing 

 the disease in healthy pigs. They found that the virus passed 

 through the Berkefeld or Chamberland F or B filters. This 

 is the disease that was thought to be due to B. suipeslifcr or 

 the bacillus of hog cholera. The findings of de Schweinitz and 

 Dorset were confirmed by Ostertag 18 in Germany. The virus 

 of this disease in serum or organ juice is killed when exposed 

 for one hour at 78 C. It is also found to be destroyed in one 

 week in buried organs undergoing putrefaction. Uhlenhuth, 19 

 Huebner and others have found that the English swine fever, 

 American hog cholera and German Schweinepest, are caused 

 by a filterable virus. 



Sheep-pox. In 1902 Borrell 20 demonstrated that material 



13 Wooley. The Philippine Jour, of Science, 1906, p. 581. 

 "Semner. Deut. Zeit.. f. Tiermed. u. vergl. Path., Bd. XXII 

 (1897) p. 32. 



15 Kolle and Turner. Zeit. f. Hygiene, Bd. IX (1898) p. 309. 



16 Todd. The Jour, of Hygiene, Vol. VII (1907) p. 570. 



17 de Schweinitz and Dorset. Circular 44, B. A. I., U. S. Dept. 

 Agriculture, 1903. 



18 Ostertag. Zeit. f. Infek. der Haustiere, Bd. II (1907) p. 250. 

 !9 Uhlenhuth. Zoc. cit. 



"Sorrel, Compt. rendu de la Soc. de Biol., Vol. LIV (1902) p. 

 59. 



