IN SUSCEPTIBLE ANIMALS. 507 



from America corresponding- with a somewhat attenuated variety of that 

 from Germany. 



Welch (1894), as a result of his extended researches, arrives at the follow- 

 ing 1 conclusion : 



"Our own conclusion as to the bacteria of Schweineseuche and of swine 

 plague is that no difference exists between them as regards morphology, 

 culture behavior, and pathogenic effects on rabbits, mice, and other labora- 

 tory animals. Cultures of each occur which are also indistinguishable by 

 inoculation of pigs. The only difference by laboratory experiment which 

 has thus far been brought out is that there occur Schweineseuche bacilli of 

 higher degree of virulence as tested on pigs than any swine-plague bac- 

 teria which have hitherto been isolated from pigs in this country. Another 

 point to be considered in this connection is that Schweineseuche occurs as 

 an independent disease in Germany without association with hog- cholera, 

 whereas swine plague has not been shown to prevail with the same inde- 

 pendence as an epizootic in this country.'' 



Silberschmidt (1895) arrives at a different conclusion from that reached 

 by Smith, Welch, Bang, and others, He believes that the diseases of swine 

 known as hog cholera, swine plague, and infectious pneumo-enteritis are all 

 due to one and the same bacillus, which, however, varies considerably both 

 in its morphological characters and its pathogenic power. In view of the 

 results previously reached by equally competent bacteriologists, and especially 

 by Smith and by Welch in this country, we are not disposed to accept the 

 view maintained by Silberschmidt. 



Smith has described several varieties of the hog-cholera bacillus, and in 

 his account of the "hog-cholera group of bacteria " shows that the Bacillus 

 enteriditis of Gartner and the Bacillus typhi murium of Loffler belong to 

 this group. The characters of the different varieties (or species?) belonging 

 to the group are given by Smith in detail (United States Department of Agri- 

 culture, Bureau of Animal Industry, Bulletin No. 6, 1894), and the follow- 

 ing 1 general statement is made: 



" If we attempt to sum up those characters which are to circumscribe the 

 hog-cholera group of bacteria we are at once confronted by the scarcity of 

 common characters. Pathogenesis, though of great importance from the 

 standpoint of pathology, is probably the last character acquired and 

 evidently the most variable and most readily lost. If we base the unity 

 of this group on morphological and biological characters, we are like- 

 wise met by variations in size, absence of motility, variations in the ap- 

 pearance of the colonies. There are, however, certain underlying char- 

 acters, as expressed by the behavior of these bacteria in bouillon con- 

 taining dextrose, saccharose, and lactose, which I think will serve as a very 

 important group character, differentiating such groups sharply from the 

 colon group. I would therefore suggest that for the present all bacteria 

 whose size approximates that of this group, which do not liquefy gelatin, and 

 whose fermentative properties are the same as those described for this group, 

 should be ranged under it. Future investigations into the biochemical char- 

 acters of these varieties or sub-species may reveal other differential charac- 

 ters, but the time has not yet come when such laborious work will be under- 

 taken oi a sufficiently extensive scale to be of any service in differentiating 

 varieties and sub-species." 



Selander in 1890, and Metschnikoff in 1892, have reported a rapid increase 

 in virulence of the bacillus of hog cholera by successive inoculations in 

 rabbits or pigeons. Moore (1894) has shown that this is a mistake, and that 

 the bacteriologists named probably did not experiment with cultures of the 

 hog-cholera bacillus, as they supposed, but that their experiments were 

 made with the bacillus of swine plague Bacillus septicaemias hemorrhagi- 

 cae which when passed through a series of rabbits attains a notable increase 

 in pathogenic virulence. 



In a recent article, Klein, of London (1895) says: " The bacillus of 

 English swine plague, which I described in 1884, in Virchow's Archiv, as 



