222 QUEENSLAND AGRICULTURAL JOURNAL. [1 Mar., 1899. 
This situation continued while the investigations of the disease were being 
pursued, and must have continued indefinitely but for this scientific work. 
In the years from 1880 to 1882, inclusive, the writer made inoculation 
experiments with from twenty to twenty-five head of cattle, from which it was 
shown that the disease might be transmitted by hypodermic inoculation with 
the blood of animals that were suffering from it. Some of the inoculated 
animals died and others recovered. ‘hese experiments were the starting-point 
of the scientific researches. They indicated, first, that there was something 
in the blood of affected animals which would cause the disease ; and, secondly, 
that it was possible to produce a mild form of disease in this manner from 
which the greater part of the animals would recover. 
The next important step was the discovery by Dr. Theobald Smith, working 
_ under the writer’s direction, of a parasite in the red globules of the blood of 
animals suffering from this disease. This minute micro-organism was first 
observed in 1886, and was carefully studied during the years 1888 and 1889, at 
which time the conclusion was reached that it was an important factor in the 
production of the disease. 
About this time, probably in ‘the latter part of the year 1888 or early in 
1889, the writer happened to meet Hon. D. W. Smith, of Illinois, at a hotel 
in the city of New York, and, while at dinner, the subject of Texas fever formed 
the leading topic of conversation. Mr. Smith earnestly urged a thorough investi- 
gation to determine if the ticks usually carried by cattle from the infected 
distriet play any part in the production of the disease. He urged that the 
stockmen of his section were convinced by observation that the tick was in 
some way responsible for the infection, and he was strong in the same belief. 
This view as to the tick had been held for many years by some of the cattlemen 
of the south-west, but was at best only a conjecture, and was offset by equally 
strong convictions of others that the infection was disseminated by the saliva, 
the urine, the manure, and even the discharges from the sore feet of southern 
cattle. Mr. Smith advanced the theory that the disease might be caused by 
the small ticks, which were found on the grass in large numbers in the pastures 
where the southern cattle had been. He thought that these must be swallowed 
with the food, and might poison the system and produce the fever. 
Scientific investigators had never been favourably disposed toward the tick 
theory. There was no precedent among the epizootic diseases which had been 
studied for such a theory, and it was thought that the characteristics of Texas 
fever were inconsistent with the conclusion that the infection was due to the 
ticks. The discovery of a parasitic micro-organism in the blood globules was 
also supposed to bear against the tick theory, because at that time it had 
oceurred to no one that two entirely different kinds of parasites co-operated 
and were necessary to the spread of the disease. 
There was, however, one fact which apparently had not been appreciated 
by others which strongly inclined the writer to the view that the ticks had 
something to do with the spread of Texas fever. When the infected district 
(that is, the district from which cattle carried the contagion) was investigated 
and mapped, it was found to correspond exactly to the district which was the 
habitat or home of the southern cattle tick (Bo-ophilus bovis). That this 
correspondence should occur over such a wide extent of territory, and that 
there should still be no connection between the parasite and the disease 
appeared to be one of the most remarkable coincidences observed in all 
Nature. 
It was deterinined that all doubt in regard to this question should be 
speedily removed. To that end Dr. I. L. Kilborne, who was then superinten- 
dent of the experiment station of the Bureau of Animal Indusiry, was 
conferred with and instructed to carry through a series of experiments which 
would prove either that the tick was responsible for the spread of the disease, 
or that it was innocent of the charges which had been made against it. 
The first experiment to decide this point was made early in the summer of 
1889. Seven head of cattle from the eastern part of North Carolina were 
