BACTERIA IN DAILY LIFE 



Now Koch's method for the compassing of 

 rinderpest differed from both the systems above 

 mentioned, inasmuch as he neither employed 

 artificially weakened cultures of the virus, or an 

 anti-toxic rinderpest-serum ; instead he took one 

 of the natural secretions of an animal infected 

 with rinderpest, and by injecting this into a 

 healthy animal it was discovered that the latter, 

 as is the case with a vaccine, suffered only local 

 and temporary discomfort, and acquired pro- 

 nounced immunity from the active virus. The 

 secretion selected by Dr. Koch and his assistant, 

 Dr. Kolle, for this purpose was the gall, and it 

 might be supposed, from the fact that its inocula- 

 tion into healthy animals did not communicate the 

 disease, that the rinderpest bacteria were absent 

 from the gall. But this is not so, for Dr. Kolle 

 has succeeded in isolating the latter from the 

 gall of infected animals, and, moreover, has proved 

 them on isolation to possess their full complement 

 of virulence. Further investigations made by 

 Koch and Kolle have shown that the explana- 

 tion of this seeming anomaly is to be found in 

 the fact that the gall of an animal suffering from 

 rinderpest contains a substance which prevents the 

 migration of the rinderpest bacteria, with which 

 it is associated, from the point of inoculation. 

 Hampered in their movements by the controlling 



