IN SUSCEPTIBLE ANIMALS. 447 



numerous in the interior of the leucocytes, which are sometimes com- 

 pletely filled with them. 



Pasteur's first studies relating to the etiology of "rouget" were 

 made, in collaboration with Chamberlain, Roux, and Thuillier, in 

 1882. His description of the microorganism to which he attributed 

 the disease does not correspond with that subsequently isolated by 

 Loffler an I by Schiitz ; but the last-named bacteriologists, and Schot- 

 telius also, found the characteristic rothlauf bacillus in cultures from 

 his laboratory which had baan prepared for the protective inoculation 

 of swine " vaccins." Pasteur found, by experimental inoculations 

 of his bacillus of rouget into pigeons, that the virulence of his cul- 

 tures was increased by successive inoculations through a series of 

 these birds, as shown by the oocurrenca of daath at an earlier date, 

 and also by the fact that blood taken from the last pigeon in a series 

 was more virulent for swine than that from the first or from an in- 

 fected pig. On the other hand, the virulence was diminished by in- 

 oculations into rabbits ; and, by passing the bacillus through a series 

 of these animals, a vaccine was obtained which produced a com- 

 paratively mild and non-fatal attack in swine. In practice the U33 

 of two different vaccines is recommended, a mild " attenuated " 

 virus being first inoculated, and, after an interval of twelve days, 

 a second vaccine having greater pathogenic potency. These inocula- 

 tions have been extensively practised in France, and that immunity 

 from the disease may be secured in this way is well established, hav- 

 ing been confirmed in Germany by Schiitz, by Lydtin, and by Schot- 

 telius. There is, however, some doubt as to the practical value of 

 the method, inasmuch as a certain number of the inoculated animals 

 die, and there appears to be danger that the disease may be spread 

 by the alvine discharges of inoculated animals. In a region where 

 the annual losses from tho disease are considerable, and where the 

 soil is, perhaps, thoroughly infected with rothlauf bacilli, protective 

 inoculations probably afford the best security against loss. But 

 under other circumstances the quarantine of infected animals and 

 thorough disinfection of the localities in which cases have occurred 

 will probably prove a better mode of procedure. 



68. BACILLUS COPROGENES PAKVUS. 



Synonym. Mauseseptikamieahnlicher Bacillus (Eisenberg). 



Obtained by Bienstock from human faeces. 



Morphology. A very minute bacillus, which is but little longer than it 

 is broad, and might easily be mistaken for a raicrococcus. 



Biological Characters. Grows very slowly on nutrient gelatin, forming 

 a scarcely visible film along the line of inoculation, which at the end of 

 several weeks is scarcely one millimetre wide. Is not motile. 



Pathogenesis. In white mice an extensive O3dema is developed at the 



