340 TEXAS FEVER 
The inoculation disease appears in from eight to ten days after the 
injection of the blood. It lasts from one to two weeks. The symp- 
toms are occasionally of a still shorter duration, but the altered condi- 
tion of the blood persists in some cases for a much longer period. 
Dalrymple, Dodson and Morgan, of the Louisiana Experiment 
Station, conducted experiments along this line. They showed that 
immunity against a fatal attack of Texas fever can be conferred on 
susceptible cattle by inoculation with the blood of a native Southern 
animal or one which has recently been rendered immune. 
Ligniéres reports good results in the vaccination of cattle against 
piroplasmoses in Argentina. He also reports that animals that are 
resistant to P. bigeminum may be very susceptible to P. argentinum. 
He used, in South America, two vaccines: the first, blood taken from 
diseased cattle at the time it contained the greatest number of para- 
sites and kept at 5° to 8° C. for 30 days, when it was injected intra- 
venously in doses of 10 cc. each. This produced a mild form of disease 
followed by immunity. Ten days after the first injection, he injects 
1 cc. of blood equally rich in piroplasma but which had been kept for 
15 days only at temperature of 5° to 8° C. This acted as a test 
noculation. 
Ligniéres found that while blood taken from diseased animals 
retains its virulence for several days, especially at a temperature of 
5° to 8° C., he also states that if the vaccine be injected under the 
skin the toxin to which its vaccination properties are due is destroyed 
before it reaches the blood stream. The preparation of vaccine from 
blood containing P. bigeminum by desiccation or freezing, he states, 
does not apply to P. argentinum because this organism remains alive 
and virulent after freezing. 
In Missouri, Connaway has immunized a few animals with the 
blood serum from immune (southern) cattle. In Mississippi, Robert 
has tried the serum for both prevention and treatment with somewhat 
similar results. In Virginia and Oklahoma the disease and its preven- 
tion have been studied. In Texas, Francis immunized cattle with 
most excellent results. He has pointed out the value of immunizing 
young (2 to 6 weeks old) calves by artificially infesting them with 
ticks. In Australia the problem of immunizing cattle against “tick 
fever’ has become a matter of serious consideration. Certain Euro- 
pean writers claim that immunity can not be permanently induced by 
artificial injections. Schroeder has shown that the parasite remains 
