^00 THE AMERICAN MONTHLY [Jul 



With these purposes in view, the writer, in 1879 and 

 1880, inoculated six head of cattle and drenched three 

 with liquids that appeared most likely to contain the con- 

 tagion. Two of these animals had an attack of fever, one 

 being so seriously affected that it became quite weak and 

 emaciated. In 1882 three more animals were inoculated, 

 one of which became sick in ten days and died three days 

 later of acute Texas fever. This was the first demonstra- 

 tion of the inoculability of the disease, and it proved that 

 a mixture of blood and splenic pulp contained the conta- 

 gion. 



In 1886, Dr. Smith, in studying microscopic prepara- 

 tions from the spleen of an animal that had died of ihe 

 disease, observed peculiar bodies in the red corpuscles 

 which were suggestive of parasitic micro-organisms. In 

 1888 and 1889 further studies of these bodies were made, 

 which led to the conclusion that they were protozoa As 

 the most prominent feature of the disease was found o be 

 a breaking down and destruction of the red corpu^cle8, 

 and as these parasites existed almost exclusively in the 

 red corpuscles of the blood, there was some reason to t tiink 

 they might be the cause of the disease. 



At this period, having completed the survey of the per- 

 manently infected district, the writer observed that this 

 district corresponded almost exactly with the habitat of 

 the tick (Boophilus boms), which was almost invariably 

 found to infest the cattle that wore capable of transmit- 

 ting the disease. Taking this coincidence, with the strong 

 belief held by many cattle men of experience, that the 

 ticks had something to do with the production of the dis- 

 ease, it was determined to have this aspect of the question 

 fully investigated. Dr. F. L. Kilborne, who was at that 

 time in charge of the Bureau experiment station, was con- 

 sulted and given explicit instructions to carry through 

 one or more series of experiments with this object in view. 

 The first experiments were made in 1889, and the result 



