BIOLOGICAL PRODUCTS (VETERINARY). 
677 
temporary or passive immunity, the duration of which does not 
exceed a period of probably a month or six weeks. In the simul¬ 
taneous method a small amount of disease producing blood or 
virus is injected with the antiserum. This method is of the nature 
of a vaccination producing an active or more lasting immunity 
than that produced by the serum alone method. 
The serum alone method is indicated in herds which have 
been infected or are in close proximity to infection. The simul¬ 
taneous method in herds which are free from the disease. The 
dose of the serum is from 20 to 40 c.c. per hundred weight. 
The serum gives good results, especially as a prophylactic 
for the disease, provided it is properly prepared and admin¬ 
istered. 
Antianthrax Serum .—This serum is used to some extent in 
immunizing against anthrax, especially when an immediate pro¬ 
tection is desired. The serum is prepared by hyperimmunizing 
animals, usually sheep, first by injecting weakened cultures of 
the anthrax organisms, then by more virulent cultures. The 
serum from an animal so treated constitutes the antianthrax 
serum. The immunity produced by this product is of a tem¬ 
porary nature, but seems to be of sufficient length in many cases 
to protect the animal until it can be actively immunized with the 
Pasteur Vaccine. 
Dawson has obtained very good results with the anti-anthrax 
serum, especially when it is used in conjunction with the vaccine. 
Biological Diagnostics. 
Tuberculin is probably the most extensively used biological 
diagnostic agent in veterinary practice. It consists mainly of 
the products of the tuberculosis organisms grown in 4 per cent, 
glycerin bouillon. Many types of tuberculin have been produced 
by various workers, but the two known as “ Koch’s Old ” and 
“ Koch’s Purified ” are of special concern to the veterinarian. 
“ Koch’s Old Tuberculin ” is prepared by inoculating flasks 
of 4 per cent, glycerin bouillon with the tuberculosis organisms, 
incubating for a period of from six to ten weeks or longer. After 
the growth is complete the cultures are sterilized and then evapo- 
