QO The Farmer^s Veterinary Admiser. 



X. TMTvnTTTTTY BY IKOCtTLATION WITH GEEM8 MODIFIED BY 



ANOTHER GENUS OF ANIMAL. 



In 1878 Burdon-Sanderson and Duguid inoculated anthrax 

 on guinea-pigs for several generations of the poison, and 

 from the guinea-pigs inoculated several cattle, all of which 

 passed through a mild form of tha disease and without ex- 

 ception recovered in five days. The same cattle, afterward 

 inoculated with very virulent anthrax fluids, again sickened, 

 but in no case with a fatal result. These experiments were 

 repeated and confirmed by Greenfield a year later. 



In 1879 I inoculated swine-plague matter on a lamb and 

 a rat and conveyed the infection from these animals back to 

 pigs, the latter taking the disease in a mild form, and show- 

 ing the characteristic lesions on post-mortem examination 

 after the recovery had been well advanced. As a first at- 

 tack protects against a second, we assume that these pigs had 

 been rendered insusceptible. 



In 1884 Pasteur inoculated the virus of canine madness 

 on monkeys, and inoculated it from the apes back on rabbits 

 and dogs, producing in the latter a non-fatal disease which 

 protected the system against a second attack. 



This method is doubtless capable of very gi'eat extension 

 in other plagues. 



XI. IMMUNITY BY INOCULATION WITH GEEMS GROWN IN DIF- 



FEEENT LIQUIDS OE SOLIDS. 



It is well established that ferments produce different pro- 

 ducts and assume varied forms as grown in different liquids. 

 So with disease-germs. In 1878 I found that the virus of 

 swinei-plague preserved in wheat-bran was constantly fatal, 

 and in 1880 that similar virus cultivated in previously steril- 

 ized milk, egg albumen, and urine, respectively, produced 

 only mild attacks, which protected against the usual infec- 

 tion. 



