112 
J. W. CONNAWAY. 
great in calves of the beef breeds intended for sale, instead of 
experiment. 
A quarantine pasture has been maintained at the Missouri 
Station through four summers, and during this time no deaths 
have occurred in the farm cattle grazing in an adjacent pasture, 
separated by a space of fifteen feet. 
From the above we may conclude that complete immunity 
is not acquired by the young animal through a single mild in¬ 
festation with fever ticks, but that the immunizing process is a 
gradual one requiring several months for its completion. 
The preferable way of effecting immunity by this method 
would be to give a mild infestation as early in the season as 
possible, and reinfest at intervals with a gradually increased 
number of ticks ; permitting the animal to be free from ticks 
for a short time before reinfesting and seeing that all fever from 
the previous infestation had passed. Gross reinfestation from 
the pasture, before the animal is ready to bear it, may be pre¬ 
vented by one change to a clean pasture during the season. 
One of the most important requisites in immunizing is that 
the calf be well nourished throughout the immunizing period. 
Otherwise stunting of the animal will occur, and occasionally a 
fatal relapse. 
From the fact that exclusive hand feeding is not desirable 
in raising calves of the beef breeds, the tick-infestation method 
cannot come into large use in immunizing these animals, unless 
the breeder finds it profitable to maintain a herd of immune 
cows. There are no very serious difficulties in the way of main¬ 
taining infected pastures on northern stock farms, and the ani¬ 
mal that has stood the test of tick-infestation at the north car¬ 
ries with him his own certificate of immunity, namely, the ticks 
themselves or their ineffaceable scars. 
The blood inoculation method to be described may however 
meet all requirements. 
(To be continued.) 
