BACILLI OF SWINE ERYSIPELAS. 307 



mentally tested in a large number of animals by Lydtin 

 during April, 1885, in the Duchy of Baden. 



Pasteur found that the virus of this disease was more 

 virulent for swine when it had passed through the 

 bodies of several pigeons in succession, and had attained 

 the maximum of its virulence in the case of pigeons ; 

 that, on the other hand, the danger of the virus as 

 regards swine was markedly diminished when it was 

 inoculated through a series of rabbits. If Pasteur in- 

 oculated the erysipelas bacilli into the thoracic muscle 

 of a pigeon, the latter died in from six to eight days, 

 having previously exhibited the external symptoms of 

 chicken cholera. If, now, the blood of the first pigeon was 

 inoculated into a second, the blood of the second into a 

 third, and so on, the latter animals died much more 

 quickly than the first, and the blood of the last pigeon 

 was much more virulent for the swine than was the 

 most poisonous product from a swine which had died 

 of spontaneous erysipelas. On the other hand, by re- 

 inoculation from rabbit to rabbit, an increase of the 

 virulence of the virus in these animals was observed, and 

 ultimately the animals died without exception, and more 

 quickly than after the first inoculation. If now Pasteur 

 inoculated the bacilli thus acclimatised in rabbits on 

 swine the latter became ill, but did not die, and were 

 protected, after recovery, against the most virulent 

 erysipelas poison. (Pasteur always speaks in his papers 

 of a round microbe, which, when taken from the blood 

 of rabbits, was larger than in swine, and which had the 

 form of the figure 8.) 



Acting on these principles Pasteur has prepared two Control 

 vaccines with which young swine the age is from 

 8 to 11 weeks are inoculated by subcutaneous injection vaccine 

 on the inner surface of the thigh at an interval of 

 twelve days. By this means an immunity is obtained 

 which lasts about a year in other words, is sufficient 

 to enable the animal to pass through the period of 

 life when it is most liable to the erysipelas infection. 

 These vaccines have been recently examined bacterio- 

 logically by Schiitz and Schottelius, and their action on 



