248 BLACK LEG 
planting trees and cultivation. In Denmark the disease has decreased 
considerably on account of such treatment. 
Vaccination. Several methods of fortifying exposed animals 
against the infection of symptomatic anthrax virus have been pro- 
posed. In 1880, Arloing, Cornevin and Thomas demonstrated at 
Chaumont that animals injected with the filtrate of cultures of this 
virus into the jugular vein were protected against inoculation with the 
strong virus. It was found, however, that this method was difficult, 
as the vein had to be exposed and the greatest care was necessary to 
prevent infection of extra vascular tissue in introducing and with- 
drawing the syringe. Later these investigators attenuated the virus 
by heating it to a temperature of 100 to 104° C. and injecting it into 
the subcutis of the shoulder. This gave a partial immunity which 
was reinforced after eight or ten days by a second inoculation of a virus 
that had been heated from 90 to 94° C. for six hours. They injected 
the virus where the subcutis is quite dense, such as at the end of the 
tail where only local swellings would occur. This process is known as 
“the French method,” Arloing’s or the “Lyons method.” 
In 1888 Kitt proposed a single injection method using a virus 
attenuated by heating at a temperature of from 85 to 90° C. for six 
hours. A single injection of this vaccine would further confer 
immunity. He further modified Arloing’s method by making the 
injections in the shoulder regions where the skin is looser and the 
operation easier. Later, Kitt made further important investigations 
concerning preventive vaccines for this disease. 
In the fall of 1896, investigations looking to the preparation of a 
black quarter vaccine were begun in the Bureau of Animal Industry 
at Washington by Dr. Norgaard under the direction of Dr. Salmon. 
The various European methods were tried. The one finally adopted 
consists of a single vaccine, the Arloing principal with Kitt’s modifica- 
tion. 
The material used for the vaccine is obtained from a fresh blackleg 
tumor, by pounding the muscle tissue in a mortar with the addition 
of a little water and squeezing the pulp through linen cloth. The 
* juice is spread in layers on plates and dried quickly at a temperature 
of about 35° C. This temperature does not in the least affect the 
bacteria, and the dry virus obtained in this way retains a high degree 
of virulence for two years or longer. 
When vaccine is to be prepared, the dried material is pulverized 
and mixed in a mortar with two parts water until it forms a semifluid 
