410 QUEENSLAND AGRICULTURAL JOURNAL. [1 Nov., 1897. 
resulted from the injection of ‘ recovered blood.” In other instances, however, 
no such reaction has been discoverable ; as witness the case of ten head of tick- 
infested, mixed cattle, inoculated by Mr. Robert Archer,* which showed’ no 
reaction whatever when injected with doses varying from 80 to 240 minimst+ of 
recovered blood; and also the ease of another experiment, recently carried 
out at Hughenden, where fourteen head of clean, susceptible, mixed cattle 
showed no reaction from the injection of 4 c.c., and subsequently of 16 c.c., of 
blood from an animal which had but just recovered from a very severe attack 
induced by the injection of virulent blood. 
That a very considerable protection was conferred in these cases, in spite 
of the total absence of all discernible reaction, is almost certain; for when the 
ten head inoculated by Mr. Archer were subsequently exposed to virulent ticks, 
along with an equal number of controls, three of the former and nine of the 
latter succumbed to tick fever. This result cannot, perhaps, be regarded as 
very successful, but a difference of 60 per cent. in favour of the inoculated 
cattle must be regarded as unquestionable evidence of the protective value of 
the process. As to those inoculated at Ifughenden: When eight of them, 
together with one control cow, were tested by the injection of virulent blood, 
_ none showed any rise of temperature except the control cow. Her tempera- 
ture reached 107 degrees Fahr. on the thirteenth day, and at the time of 
writing she seems likely to die. 
These experiments seem to indicate very clearly that the protective value 
of recovered blood cannot be gauged by the amount of reaction it causes. They 
also seem to suggest that its eflicacy may be due, in part at any rate, to the 
presence of some abnormal product or products analogous to the anti-toxins 
of bacterial diseases. This question is still shrouded in mystery. The difference 
between the blood of susceptible cattle and that of immune cattle is too subtle 
to be recognised by any physical tests. But it must obviously be a very 
profoundone. In the ordinary course of things, we have reason, from analogy, 
to believe that the change is brought about by a specific reaction. Where, 
however, immunity is brought about in the absence of reaction, as in the 
experiments just mentioned, it seems possible that, as has been suggested 
to the writer by Dr. J. H. Connoway of the Missouri University, products 
differing from the normal, even though not rising to the dignity of anti-toxins, 
may be present in the blood of recovered animals, and these may, possibly, 
have some share in bringing about the development of the like protective 
products when injected into susceptible animals. Here, however, are problems 
awaiting solution ! 
Tn regard to this question of possible toxins and anti-towins associated 
with tick fever, it may be remarked, in passing, that, if the views that have 
been suggested as to the nature of reaction are accepted, it can hardly be 
supposed that any pure toxin, or pure anti-tcwin, is present in the blood of 
acutely diseased beasts. The micro-organisms might be assumed to produce a 
toxin, and the vital resistance of the animal invaded an anti-toxin. Yet, in the 
violent reaction of opposing forces which constitutes tick fever, it can never be 
possible to foretell which will get the upper hand,‘or at any given moment to 
say definitely whether the attacking foxins of the invadin g microparasites, or the 
defending anti-towins of the invaded organism are in the ascendant. No reaction 
in susceptible cattle’has been produced by the injection of sterilisedt virulent 
blood, which seems to indicate that there is at any rate no free toxin present, 
We have, however, no absolute evidence on this subject. The presence 
of some substance analogous to an anti-toxin, or at any rate of some 
metanormal product, as Dr. Connoway would call it, may, perhaps, with some 
reason, be assumed to exist in the blood of recovered animals, because the fact 
of their immunity, as compared with susceptible animals, indicates that there 
* These cattle were infested with ticks, but were apparently healthy. 
+ Equivalent to about 4°3 to 12°9 c.c. 
~ The same experiment with filtered virulent blood will shortly be undertaken by the 
Government Bacteriologist. . ; : 
