Protective vaccinations 475 



made to replace the Pasteurian metliod by some other method less 

 risky. Hence, since the discovery of the principle of sero-therapy 

 several investigators have sought to apply it to swine erysipelas. 

 Emmerich and Mastbaum^ were the first to demonstrate that tlie 

 blood of rabbits, immunised with the bacilli of this disease, acquire 

 a very marked protective power. They have even attempted to con- 

 struct from the results of their researches methods which might be 

 applied practically. It is especially however to Lorenz^, a Darmstadt 

 veterinarian, that we owe the first practical application of this method. 

 He prepared protective serums by injecting erysipelas bacilli into 

 rabbits and pigs, and demonstrated that the inoculation of these 

 serums, when combined with that of the living bacilli, confened upon 

 pigs a sufficient immunity and one that was set up immediately after 

 the introduction of the serum. According to Lorenz's method it is first 

 necessary to give a protective injection of serum ; some days (3 — 5) 

 afterwards this is followed by an inoculation of living bacilli coming 

 from the attenuated erysipelas known in Germany under the name of [498] 

 " Backsteinblattern." About two weeks later a further injection of 

 the same bacilli, but in double quantity, is given. This method, there- 

 fore, involves three vaccinal injections as against two in the Pasteurian 

 method. It is consequently dearer than the latter, but, as it presents 

 certain undeniable advantages, an attempt was made to introduce 

 it into veterinary practice. But being much more complicated en- 

 deavours were made to simplify it. Voges and Schiitz, by methods 

 which have remained secret, soon obtained a more active serum, 

 and finally Leclainche^ of Toulouse, after demonstrating that the 

 horse is the best animal for the production of a very active serum, 

 succeeded in devising a method of vaccination as simple as it Avas 

 effective. He gave to it the name of " serum- vaccinations." The first 

 inoculation is made with a mixture of specific serum and a culture of 

 living and virulent bacilli. This inoculation is well borne by all pigs 

 and may be made without any regard to the age of the animal The 

 immunity is set up immediately after the injection of the mixture, but 

 it is not sufficiently durable for the requirements of practice. For 

 this reason Leclainche followed up the first injection by a second, which 



1 Arch.f. Hyg., Miinchen u. Leipzig, 1891, Bd. xii, S. 275. 



2 Deutsche thierdrztl. Wchnschr., Karlsruhe, 1893, Bd. i, SS. 41, 85 ; Centralbl.f. 

 Bakteriol. u. Parasitenk., Jena, 1893, Bd. xiii, S. 357 ; Deutsche Ztschr.f. Thiermed., 

 Leipzig, 1894, Bd. xx, S. 1. 



3 Bev. vet., Toulouse, 1900, t. lvii, p. 346. 



