HOW WILL THE ERADICATION OF THE CATTLE TICK 
BENEFIT THE PRACTICING VETERINARIAN? 
By A. C. Stever, Veterinary Inspector, U. S. Bureau of Animal Industry. 
(Continued from April Issue.) 
Immunity .—Through the experiments of the United States 
Bureau of Animal Industry, 1892 and 1893, it was suggested 
that the production of a mild non-fatal attack of Texas fever in 
cattle afforded a very considerable protection against the disease. 
The methods advanced for producing such a mild, non-fatal 
attack were: 
First—The artificial inoculation, intravenously or subcu¬ 
taneously, of defibrinated blood into a now immune cow. 
Second—The less certain way consists of the exposure of 
non-immune animals to ticks by confining them in inclosed pas¬ 
tures after scattering ripe-egg-laying ticks over the grass. 
From 1895 to I ^97 additional experiments were conducted 
by the bureau with the object of further demonstrating the pos¬ 
sibility of immunizing cattle against Texas fever by the use of 
blood obtained from southern cattle. While the results obtained 
seemed to be satisfactory, still, from actual field experience and 
through information obtained from various scientific men en¬ 
gaged in the work of tick eradication, it seems to me that the 
term immunity in connection with this disease is really a mis¬ 
nomer, because cattle can pass through either the acute or chronic 
form, be freed of ticks, placed on free premises, and should their 
systems become devitalized through any predisposing cause, such 
as exposure, etc., probably they will contract the disease several 
years after they have attained this stage of so-called immunity. 
Microbiology .—The piroplasma bigeminum passes through a 
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