1 Dec., 1898.] QUEENSLAND AGRICULTURAL JOURNAL. 449 
by the mechanical misery and irritation they cause, and by the constant 
abstraction of small quantities of blood. As regards the last we know well 
that the constunt loss of even a small quantity of blood in any animal has a 
quite different physiological effect to that produced by a single abstraction of 
much larger quantities, or even repeated bleedings at comparatively distant 
intervals. : 
But I, personally, iricline to the belief that, in addition to these influences, 
there is another factor at work, and that the tick, like most other creatures of 
its kind, introduces some peculiar poison of its own. I am not now referring to 
any microparasite or organism foreign to itself with which it may be 
contaminated. Of that I shall have to speak directly. I refer to a poison 
comparable to that ordinarily introduced by mosquitoes, fleas, gnats, sandflies, 
and the like. I know of no way in which this assumption can be directly 
proved; but it seems to me, on the face of it, improbable that the cattle tick 
alone is unprovided with some such poison of its own, and, considering how 
virulent the poison of other species of ticks is known to be, I should say some 
pretty active poison. ‘Lhe local irritation or inflammation caused by cattle 
ticks in animals that have not become accustomed to their presence is strictly 
comparable to similar inflammation brought about on the face and hands of the 
“new chum” by the welcoming activities of the mosquito. But, as we all 
know, the “new chum” becomes the “old chum,” and, although the mosquitoes 
still favour him, he eventually acquires an almost complete immunity to the 
inflammatory effects. The same thing appears to happen to cattle and horses 
that have become inured to ticks. ‘Lhe explanation in all these cases is 
probably the same—viz., that there is producéd in the blood of the man, horse, 
or bullock some substance or quality which antagonises or counteracts the 
respective poisons of these insects—though I should not properly call the tick 
an insect, as he is not justly entitled to that rank, and belongs to a somewhat 
lower natural order. beh AF) 
Another reason I have for suspecting an organic chemical poison peculiar 
to the tick—though I will not now dilate upon it —is that in the blood of tick- 
infested cattle, where no Texas fever has ever appeared, there are frequently 
to be found what I take to be evidences of the breaking up of what are known 
as the nuclei or kernels of the white-blood corpuscles into small highly 
refracting bodies which, when free in the blood stream, inight easily be mistaken 
for—and possibly have in certain instances been mistaken for—forms of the 
Texas-fever organism; for an erroneous observation of this kind would 
readily, account for the erroncous conclusions which have been formulated to 
the effect that tick-infested cattle are necessarily immune to Texas fever, and 
that their blood is necessarily suitable for inoculating purposes. 
Other effects are sometimes noticed on the red-blood corpuscles and on 
the coagulating power of the blood in gressly infected but still susceptible 
cattle, but of a quite different kind to those seen in cattle suffering from Texas 
fever. And these effects on the elements of the blood are, I think, such as 
may quite reasonably be referred to the action of some specific tick poison. 
Whilst on the subject of the direct harm wrought by the ticks, it may be 
mentioned that the condition of poverty, misery, and exhaustion, very 
appropriately called ‘tick poverty,” which so often wears down and destroys 
cattle when first they become grossly infested by myriads of ticks, can be 
very effectively relieved and counteracted by cleansing them of the ticks —as 
by dipping. And this fact is, I think, evidence that the particular condition in 
question is due rather to the direct effects of the ticks themselves than to 
infection of the blood with any living micro-organism. ‘Lick poverty, moreover, 
results only from gross infestment. ‘Texas fever (even in the acute and 
characteristic form often called ‘ redwater’’) is not infrequently communicated 
by ticks when so few as to be hardly discoverable; facts perfectly intelligible 
on the, view that the poverty is caused by the external multiplication of the 
ticks, just as the fever is caused by the internal multiplication of the 
microparasites. 
