4 TEXAS 



4t u That microscopical examination 

 shows the absence notwithstanding the 

 result of BilHngs investigations, in the 

 blood of an animal affected with Texas 

 fever, of other organisms when the ex- 

 aminations was made previous to death 

 or very soon after. 



5th. It has been demonstrated that 

 the intravenous injection of blood from 

 infectious southern cattle into northern 

 cattle resulted in the contraction of Tex- 

 as fever by the latter. In these cases 

 the presence of the micro-parasite was 

 demonstrated by microscopic examina- 

 tion. 

 MANEER OF TRANSMISSION. In the 



year 1889-90 Dr. F. L. Kil borne dem- 

 onstrated that the transmission of the 

 pyrosoma bigemium from southern cat- 

 tle to native northern cattle in natural 

 outbreaks is effected by the Texas fever 

 cattle tick (Boophilus Bovis) "Ox Idv- 

 ing") and by this means only, and this 

 claim is substantiated by the following 

 experiments : 



1st. Northern cattle were exposed for 



.several weeks to southern cattle, the lat- 

 ter being infested with ticks. Results : 

 The native northern cattle contracts! 

 Texas fever. Young ticks were found 

 upon them. The pyrosoma, bittemium, 

 upon microscopical examination was? 

 found in their blood. 



2nd. Northern cattle were exposed 

 to southern cattle from which ticks had 

 been removed, the ticks having been 

 picked off by hand. Result: Northern 

 cattle showed no signs of fever. 



3 r( j t A pasture was infested with ticks 

 taken from southern cattle, no southern 

 cattle were admitted to the pastures 

 Northern cattle were turned into the 

 pasture. Result: Texas fever and death. 



4th, Young ticks hatched artificially 

 from eggs laid by adult ticks picked 

 from southern cattle were placed upon 

 northern cattle. Result : Texas fever 

 and death. Pyrosoma bigemium dem- 

 onstrated in the blood by microscopical 

 examination. 



FEVER 



5th. Experiments were made showing 

 the disease is not transmissible by means 

 of the excretions of southern cattle. 



The above experiments have on nu- 

 merous occasions, been repeated and 

 corroborated, by the Bureau of Animal 

 Industry, Experimental stations of Tex- 

 as, Arkansas, Missouri, Kansas and 

 other southern states situated on and 

 below the Federal quarantine line, sep- 

 erating the infected from the non-infec- 

 ted district. Consequently, notwith- 

 standing the skepticism of stockmen 

 throughout the south we are absolutely 

 bound to acknowledge the fact that the 

 tick is the sole transmitter of the pyro- 

 soma bigemium in natural outbreaks of 

 Texas fever. 



THE TICK. There are some people who 

 still believe that the tick in itself is the 

 cause of all the trouble and that the 

 death of affected animals is due to the 

 abstraction of blood by them. The fal- 

 facy of this idea appears when we rea- 

 lize that the ticks ordinarily found upon 

 cattle dead or dying are still quite small 

 and have scarcely begun to draw blood 

 on a large scale. Moreover if such an 

 idea had any foundation how can the 

 fact be explained that there is such an 

 extensive destruction of red blood cor- 

 pubdes within the animal bod}', which 

 is demonstrated by the presence of color- 

 ing matter in ^the urine, the thick bile 

 ami the presence of pigment in the kid- 

 neys and liver? 



The cattle tick, Ixodes Bovis (Riley)or 

 Boophilus Bovis aa its name indicates 

 is a parasite peculiar to cattle in the 

 southern part of the United States, Mex- 

 ico and the West Indian Islands. It 

 belongs to the group of Artnropode and 

 to the genus Ixodes (Boophilus) which 

 is included in the order of Acanna. Its 

 life history is quite simple and easily 

 traced from one generation to another. 

 It is essentially a parasite, attaching it- 

 self to the skin and drawing the blood 



