TEXAS FEVER. 
335 
paired, and a large amount of debris that requires to be elimi¬ 
nated is added to the blood stream. 
The recovery from the fever and the maintenance of an im¬ 
mune condition depends upon the ability of the animal, ist , to 
keep in check the grozvth of the micro-parasites ; 2d , to supply 
nezv corpuscles as rapidly as they are destroyed; and jd, to re¬ 
move the waste products promptly. 
In regard to the micro-parasites, it is found that in this 
disease, unlike most others, they probably never entirely dis¬ 
appear from the blood of an animal that has once been well 
infected. In animals, however, that gain a high degree of 
immunity, the blood contains comparatively few of the miero- 
parasitis. This indicates that by some means their multiplica¬ 
tion is inhibited. It is probable that the constant presence of 
the micro-organisms in the blood has stimulated an increased 
production of white corpuscles (“ phagocytes ”), and that by 
these “ soldiers and scavengers ” of the blood many of the 
micro-parasites are destroyed. 
As to the regeneration of the red blood corpuscles, this 
is a function that is carried on normally ; for in perfect health 
the corpuscles are constantly wearing out and must be replaced 
by new ones. The increased destruction of corpuscles due to 
the micro-organisms of Texas fever simply stimulates those 
tissues normally concerned in the production of red corpuscles 
to greater activity. And it is probable that in all immune 
Southern cattle and in Northern cattle that become immune, 
a greater activity of these tissues is maintained throughout life. 
In regard to the elaboration and removal of the waste pro¬ 
ducts, resulting from the destruction of the corpuscles—the 
organs mainly concerned are the spleen, liver, kidneys and 
bowels. The importance of these organs in removing waste 
products is readily understood by anyone who has seen at the 
post-mortem of an animal that has succumbed to an acute case 
of the fever, the enlarged and softened spleen, the intensely 
yellow liver clogged with bile., and the claret colored urine. 
In immune Southern cattle the spleen is somewhat larger than 
