TEXAS FEVER 339 
cannot be transported to the infested districts (south of Texas fever 
line) unless they can be placed in fields that have been freed from 
ticks. The elimination of the disease depends therefore upon the 
elimination of Bodphilus annulatus. The government, in codperation 
with the States, has undertaken to eradicate the ticks. Thus far the 
reports are encouraging. There seems to be no reason why their 
eradication cannot be accomplished. 
Immunizing susceptible cattle. A number of investigations have 
been undertaken directed toward the development of methods for 
immunizing northern cattle against Texas fever in order to enable the 
shipment, especially of breeding stock, into the South. In 1895, the 
writer, in conjunction with Schroeder, began an immunizing experi- 
ment which was continued and reported by Schroeder in 1898. 
Young animals were selected and injected with blood taken 
directly from the jugular veins of southern animals. The injections 
were made in the fall and winter and in the spring the animals were 
placed in a highly infected field at Manchester, Va., where they 
remained for the summer. During this time they were under the 
immediate observation of Curtice, who made a careful study of the 
blood, temperature and extent of tick invasion. The results of this 
experiment are shown in Schroeder’s tabulation, which is appended. 
‘The animals were again exposed the following season without the 
development of Texas fever. 
Anima) Effect of Effect of the 
No. blood injection exposure to cattle ticks 
1 Severe reaction. Very mild disease. 
Q ds S? Well marked but mild. 
3 Very severe reaction. Very mild. 
4 = . No disease. 
5 Mild reaction. e ve 
6 ne ss Very mild. 
7 Severe reaction. No disease. 
8 ee ee oe “ 
9 a a a 
Control Animals. 
10 Died June 20. 
11 “July 9. 
12 “June 26. 
14 “July 9. 
14 Very severe disease, recovered. 
