464 DISEASES OF CATTLE. 



the growth of the parasite, in fact the largest which has thus far been 

 detected. It will be noticed that there are usually two bodies in a 

 corpuscle. These bodies are in general pear-shaped. The narrow 

 ends are always toward each other when two are present in the same 

 corpuscle. If we bear in mind that the average diameter of the red- 

 blood corpuscles of cattle is from ^gV^ to ^9- inch, the size of the 

 contained parasite may be at once appreciated by a glanco at the fig- 

 ures referred to. 



The various disease processes which go on in Texas fever, and 

 which we may observe by examining the organs after death, all result 

 from the destruction of the red corpuscles. This destruction may be 

 extremely rapid or slow. When it is rapid we have the acute, usu- 

 ally fatal, type of Texas fever, which is always witnessed in the height 

 of the Texas-fever season; that is, during the latter weeks of August 

 and the early weeks of September. When the destruction of corpus- 

 cles is slower, a mild, usually nonfatal, type of th8 disease is called 

 forth, which is only witnessed late in autumn or more rarely in July 

 and the early part of August. Cases of the mild type occurring thu3 

 early usually become acute later on and terminate fatally. 



The acute disease is fatal in most cases, and the fatality is due not 

 so much to the loss of blood corpuscles as to the difficulty which the 

 organs have in getting rid of the waste products arising from this 

 wholesale destruction. How great this may be a simple calculation 

 will serve to illustrate. If we take a steer weighing 1,000 pounds, the 

 blood in its body will amount to about 50 pounds, if we assume that 

 the blood represents one-twentieth of the weight of the body, a rather 

 low estimate. According to experimental determination at the Bureau 

 Station, which consists in counting the number of blood corpuscles 

 in a given quantity of blood from day to day in such an animal, the 

 corpuscles contained in from 5 to 10 pounds cf blood may be destroyed 

 within twenty- four hours. The remains of these corpuscles and the 

 coloring matter in them must either be converted into bile or excreted 

 unchanged. The result of this effort on the part of the liver causes 

 extensive disease of this organ. The bile secreted by the live" cells 

 contains so much solid material that it stagnates in the finest bile 

 canals and chokes these up completely. This in turn interferes with 

 the nutrition of the liver cells and they undergo fatty degeneration 

 and perish. The functions of the liver are thereby completely sus- 

 pended and death is the result. This enormous destruction of corpus- 

 cles takes place to a large extent in the kidneys, where a great number 

 of corpuscles containing the parasites are always found in acute cases. 

 This accounts largely for the blood-colored urine or red water which 

 is such a characteristic feature of Texas fever. The corpuscles them- 

 selves are not found in the urine; it is the red coloring matter, or 

 hemoglobin, which leaves them when they break up and passes into 

 the urine. 



