78 CONTAGIOUS DISEASES OF DOMESTICATED ANIMALS. 



when carried further south, but the great uncertainty which at present 

 exists witli regard to the exact location of this line makes it extremely 

 doul)tful if these farms have been correctly located. A numl)er of ex- 

 tensive breeders who have a very intelligent idea of the nature and 

 effects of this disease have recently expressed to me their high appre- 

 ciation of the work now being done by the Department of Agriculture 

 toward establishing the boundary of this infected district. It is be- 

 lieved that definite knowledge in regard to this will relieve them from 

 many of the causes of embarrassment connected with the shipment of 

 thoroughbred cattle to the South. 



INVESTIGATIONS OF SWINE PLAGUE. 



In a communication of M. Pasteur to the Paris Academy of Sciences 

 (Comptes Rendus, 1883, p, 11G3) it was asserted : 



1. That the microbe of swine plague is a dumb-bell micrococcus. 



2. That pigeons are very susceptible to the virus, and passing this 

 through a succession of these birds increases its activity. 



3. That rabbits are also suscei)tible, and passing the virus through 

 a succession of these animals attenuates it to such an extent that if pigs 

 are inoculated with it they only contract a slight illness which grants 

 them immunity from subsequent attacks. 



To these assertions Dr. Klein (Vet. Jr., 1884, July, p. 39) replies : 



1. That M. Pasteur has overlooked the true microbe, and that this is 

 a bacillus and not a micrococcus. 



2. That all of his (Klein's) inoculations of pigeons with virus taken 

 directly from diseased swine — virus which invariably produces the dis- 

 ease in swine and other susceptible animaLs — and with his artificial cul- 

 tures of the organism of swine fever, produced absolutely no effect, 

 either general or local. 



3. That it is impossible to say whethei' M. Pasteur's rabbits died of 

 swine fever or of septicjvmia, though he (Klein) had shown in 1877 that 

 rabbits are susceptible to swine fever when inoculated from material 

 directly derived from the pig. 



4. He adds in an addendum that he has recently satisfied himself 

 that the artiticial cultivation of the virus in the organs of mice or ral)- 

 bits by inoculating these from diseased swine will produce a mild form 

 of swine plague from which the animal quickly recovers, aiul is thereby 

 I)rotected from the disease. 



It is very evident that before any safe method of protective inocula- 

 tion or vaccination can be adopted we must be satisfied as to the nature 

 of the virus, liabbits and mice are both subject to septic;emia, and 

 it is quite certain, from the difference in the microscopical appearance 

 of the germ describe<l by these two inve^stigators, that either the one or 

 the other had cultivated and inoculated with a septic virus. Dr. Klein 



