HISTORY 237 



which had long been known in certain localities was more 

 widely scattered and finalh- it came to be an important barrier 

 to the cattle traffic. In 186S, the disease seems to have made 

 its first important impression upon the American people. In 

 June of that year, Texas cattle were shipped up the Mississippi 

 river to Cairo and thence by rail into the states of Illinois and 

 Indiana where they caused during the summer enormous losses 

 from this disease. Cattle from these states shipped east brought 

 the disea.se with them. The cattle commissioners of New York 

 and the Board of Health of New York City endeavored to check 

 the importation of such cattle. The disease was carefully inves- 

 tigated at that time but nothing beyond a very accurate descrip- 

 tion of the gross lesions was obtained. Later Dr. D. E. Salmon 

 determined the boundary line between the non-infected and 

 the permanently infected districts, or what is now known as 

 the Texas Fever line (vSee Plate VII). In 1889, the Bureau 

 of Animal Industrj- undertook a systematic investigation into 

 the nature of this disease, which resulted in the same 

 year in the discover}- of its specific cause by Dr. Theobald 

 Smith and later the demonstration of the fact that the disease 

 is transmitted from southern to northern cattle through the 

 medium of the cattle tick. Prior to this (1888) V. Babes had 

 found an intraglobular parasite in the blood of cattle suffering 

 from an epizootic disease (hemoglobinuria) in Roumania. 

 \Miile at first these diseases were thought to be different in 

 their etiology- the}- are now believed to be identical. Recently 

 a number of investigations have been made b}- the Bureau of 

 Animal Industry, the State Experiment Station and State 

 Board of Agriculture of Missouri, the Louisiana Experiment 

 Station and b}- the Queensland Government, Australia, for the 

 purpose of obtaining a practical method for the production of 

 immunity against Texas fever in susceptible cattle. Although 

 the results thus far obtained are promising aa they are often 

 successful, the methods must still be considered in the 

 experimental stage. 



§ 181. Geographical distribution. In the United 

 States the distribution of Texas fever corresponds with that 

 of the cattle tick {Bobphilus bovis). This includes, with possi- 



