294 QUEENSLAND AGRICULTURAL JoURNAL. [1 Aprir, 1902. 
is, the successive infestations of the southern animal from birth with the cattle 
ti¢k which confers a degree of immunity sufficient to prevent them from 
contracting a fatal case of the disease, if well cared for. It must be then plain 
to! the reader that the safest age at which northern cattle (and by northern 
cattle is meant those cattle coming from any part of the United States where 
the cattle tick is not found) can be brought south is as soon as they can be 
weaned, or at the age of six months or less. Weaning should be commenced 
earlier, however, in order to accustom the ecalf’s stomach to the herbaceous 
diet. A calf partly weaned could, after its arrival south, be allowed to nurse a 
southern cow, receive its first natural infestation with ticks, and thus acquire 
immunity the same as the southern-born animal by subsequent infestations. 
It, should be distinctly understood that no bovine, be it southern or northern, 
is safe against Texas fever unless it has been infested with ticks or immunised 
by artificial means to be described. Southern cattle reared upon tick-free 
pastures are as liable to take the disease and die as the northern animals. 
Hence it is better to allow a moderate infestation with ticks of all cattle from 
birth, since an infestation occurring for the first time, in adult life, would very 
likely kill the animal. 
, The other method of immunising susceptible cattle against Texas fever was 
first suggested and practised by Drs. Smith and Kilborne, as shown in their 
report upon the disease in 1892. It consists of the injection under the skin, 
or into the jugular vein of a northern animal, a small quantity of blood from 
a: southern animal. This method, or slight modifications of it, has been 
employed with success in Australia, and in the United States by several of the 
State Experiment Stations. Until more experience has been gained upon the 
subject the operation should only be performed by a skilful veterinarian or 
layman who realises the forces he is dealing with. In particular, the method 
as now employed is as follows:—The animal which is to supply the blood should 
be healthy, three or four years old, and must have supported successive crops 
of. ticks from birth. Such an animal is easily found in Florida. The hair is 
shaven from the neck over the jugular vein; the neck is washed with soap, 
5 per cent. solution of carbolic acid, and then with water which has been 
boiled. Put a strap round the neck and draw it tight. Place under it and 
over the jugular vein a block about an inch square. This will cause the 
vein to swell. Insert into the jugular a large hypodermic needle to which 
is attached a small peice of rubber tubing, both of which have been previously 
boiled. ‘The needle must point towards the head. Blood will now flow, and 
is to be caught in a clean tumbler and stirred with a small bundle of wires 
or other material. After stirring for a minute or two fibrin will collect 
upon the stirrer, and the blood will have lost its coagulability. Then strain 
the blood through a piece of cheese-cloth tied on to the top of a second 
tumbler. The blood is now ready for infection. A. lce. syringe with 
hypodermic needles of sufficient strength for the work is filled with the blood 
and the contents are injected under the skin of the shoulder of the animal to 
be inoculated. The place of inoculation should be cleaned in the same manner 
as that from which the blood was obtained. It is also of paramount importance 
that the blood be kept milk-warm during the process. This is best accom- 
plished by standing the tumblers in a pan of warm water. The syringe and 
all utensils should be thoroughly freed of blood and washed in 2 per cent. of 
earbolie acid solution after the work is over with. The operation must, on no 
account, be delayed after the blood is drawn. Sixty days after the first dose a 
second dose of 2cc. should be given in the same manner as the first; although 
some have given only a single dose, it stands to reason that a second one would 
fortify the initial immunity. The second dose is indicated in animals whose 
temperature did not rise to 105 Fahr. In a typical case of the fever produced 
by this means, the fever commences in a week, showing a rise to 106 Fahr., 
which continues for from five to fifteen days more, when it falls to the normal, 
but 102 Fahr. About the thirtieth day after injection a secondary milder 
fever lasting several days will occur. 
