EXPERIMENTS IN VACCINATION AGAINST ANTHRAX. 13 
TEST OF THE SIMULTANEOUS METHOD ON CATTLE AND SHEEP. 
A series of experiments was conducted at the experiment station of 
the Bureau of Animal Industry at Bethesda, Md., to establish the 
efficiency of the simultaneous method of anthrax immunization on 
cattle and sheep. 
For this purpose 6 head of cattle and 5 sheep were given the simul- 
taneous injection of anthrax serum and spore vaccine. Three weeks 
subsequent to immunization they were subjected to infection tests 
which consisted of a subcutaneous administration of 0.25 c. c. for the 
cattle and 0.125 c. c. for the sheep of blood from a guinea pig which 
had died from an artificial infection with our most virulent strain of 
anthrax. 
The microscopic examination of the blood of the guinea pig showed 
it to be heavily charged with anthrax bacilli, but in order to make 
the test as severe as possible it was deemed advisable to use such exces- 
sive amounts. Three additional cattle and two sheep were used as 
checks, receiving only the virulent blood. As a result of this infec- 
tion all animals manifested an elevation of temperature ranging from 
103° to 107° F. The control animals especially were markedly 
affected with typical manifestations of anthrax and all succumbed 
within two to eight days following infection. All but one of the 
vaccinated sheep succumbed to anthrax, but at a later date than the 
check animals. Of the immunized cattle a marked temperature reac- 
tion was noted, but all of these animals recovered with the exception 
of a small, undersized, weak calf, which died in six days following 
infection. 
While in the above test the sheep succumbed and one of the small 
calves died of anthrax, nevertheless the potency of the serum was 
demonstrated. The excessive virulent blood used for the infection 
was extraordinary and could not be compared with the amount of 
virus taken by a susceptible animal in cases of natural infection. 
FIELD TESTS. 
On June 21, 1915, Dr. K. K. Ashworth, a dairy inspector for the 
District of Columbia, notified our office that a number of deaths 
among hogs were occurring on a farm in Maryland, just outside of 
the District. The symptoms described by Dr. Ashworth pointed sus- 
piciously to anthrax. A visit was made to the farm the same morn- 
ing, and after an autopsy on several animals, followed by a bac- 
teriological examination, a definite diagnosis of anthrax was estab- 
lished. This was later conclusively verified by animal inoculation 
tests. 
At that time 7 shoats and 4 sows had died of the disease and 3 shoats, 
4 sows, and 1 boar were showing symptoms of anthrax, several of the 
