doe ir oe 
593 
will favorably modify a disease of one to three days’ duration, and that 
the serum probably keeps well for long periods of time.® 
Dschnuknosky and Iupzis experimented on a process of desiccating 
serum, which they stated was satisfactory. We followed the method 
advised by these writers and obtained a product which, while it was 
apparently useful, was soluble with such difficulty that it was valueless 
for rapid work in the field. Since the serum if kept in a cool place, 
retains its activity for a sufficient time, we have adhered to the old 
method of bottling it in liquid form. 
Method of immunizing by defibrinated blood—In addition to the 
simultaneous method and its modifications, other systems have been in 
vogue in certain localities. The best known of these consists in the 
use of defibrinated, virulent blood, introduced by Danysz and Bordet. 
The dosage varies from 50 to 200 cubic centimeters. Immunity is immediate, 
there is no reaction, and the whole process can be carried out in the field. However, 
the immunity is but temporary and the material must be perfectly fresh and 
free from pyroplasmata, trypanosomata, etc. Danysz and Bordet in following 
this procedure subsequently exposed the animals to infection. Sobernheim main- 
tains that the method is not reliable, but Hutcheon has had success with it; 
however, Theiler could immunize but 30 to 40 per cent of the exposed animals 
by this method. A great disadvantage lies in rapid deterioration of the product. 
THE COMPARATIVE VALUE OF THE METHODS OF IMMUNIZATION FROM AN 
EPIDEMIOLOGICAL POINT OF VIEW. 
Although rinderpest has great interest as a scientific study, it has in 
all probability claimed so much attention among investigators because 
of its economic importance. It is this side which naturally appeals 
most strongly to the cattle owners, especially in countries or districts 
where it is difficult to explain just what the meaning of immunization is. 
It is very difficult for the lay mind and especially for semi-educated 
people to comprehend that it is not only for the present but also for the 
future as well that we must work. They insist that we simply tide 
over existing epidemics, instead of combining such methods of work as 
will prevent future ones. 
The problem resolves itself into the treatment of clean and infected 
herds in countries where the disease is endemic and in those in which 
if is merely sporadic and dependent upon introduction from the outside. 
In the latter case, even if the serum or bile method alone is used and 
this means is supplemented by a strict quarantine against outside animals, 
the spread of the disease can certainly be completely checked. 
Greater difficulty undoubtedly arises in countries where the disease 
is endemic, where new epizodtics are constantly cropping out and where 
the outbreaks are not apparently due to outside influences. Under such 
° Theiler and Bitter state the period to be four years. 
43814——2 
