IMMUNIZING CATTLE 



365 



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. Dur- 

 ing 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. 



The inoculation disease appears in from eight to ten days 

 after the injection of the blood. It lasts from one to two 

 weeks. The symptoms are occasionally of a still shorter dura- 

 tion, but the altered condition of the blood persists in some 

 cases for a much longer period. 



Dairy mple, Dod.son and Morgan, of the Louisiana Ex- 

 periment 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 recentlj^ 

 been rendered immune. 



