Terus Fever 375 
tion of the arsenical solutions for dipping cattle has 
enabled the various states with the assistance of the 
federal government to free large areas completely of 
ticks. One attack of Texas fever gives immunity, and 
young calves are not so susceptible to the disease as are 
older animals. It is probable that the reason that 
southern cattle do not have Texas fever is because their 
immunity was acquired as very young calves at an age 
when they do not seem to be seriously affected by the 
disease. The older the animal the more serious is the 
fever as a rule. 
The Missouri and Texas Experiment Stations have 
devised a method of conferring immunity on susceptible 
cattle intended for shipment into permanently infected 
territory. It is by injecting serum obtained from the 
blood of immune eattle, and is very successful. Cattle 
intended for such shipments should be young, and 
should be taken in the fall, when the ticks are not so 
numerous and the weather is cool. 
When an outbreak of Texas fever occurs, there is 
no danger to cattle in the surrounding territory, pro- 
vided they are kept off infested ground. It is com- 
monly said by stockmen that “a wire fence will stop 
the spread of Texas fever,” but it is safer to put a 
ereater barrier, in the way of distance, as the young 
ticks may be washed short distances, or cattle may 
break through a fence and carry the ticks. After 
an outbreak of Texas fever, no susceptible cattle 
should be allowed on the infested pasture or quar- 
ters until the ticks have been destroyed by the cold of 
winter. 
