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Nearly all the cases of trypanosomiasis in cattle examined could 
be given a history, often very imperfect, of having at some recent date 
been exposed to the tsetse; but in one herd, where the history is 
reliable, the evidence is suggestive that Stonioxys and Lyperosia had 
acted as transmitting agents. 
Forty-four animals from this herd had lived at Kapopo, which 
itself is free from fly, for upwards of three years, during which time 
they had always been in good health and deaths were rare. In 
August, 1906, they were brought to Broken Hill, a distance of about 
97 miles, following as far as possible a route where tsetse were scanty 
or not known to exist, and adopting the usual precautions, such as 
marching at night. They remained in perfect health until June, 1907, 
when they came under observation. During these eleven months two 
animals had died, apparently of some acute inflammatory disease, and 
one had been destroyed as the result of an accident, and six others 
which had not been recently in tsetse areas were added. The farm 
where these cattle were kept is at least two and a half miles from the 
nearest known fly area, and they were all employed on this farm in 
agricultural work ; the three cows and three bulls grazing close to the 
buildings. On April i8th, six bullocks were sent on a journey of 
thirty miles Southwards to Mwomboshi, and returned four days later. 
G. morsitans occurs on the road travelled about eight miles from the 
farm, but it is limited to a narrow patch. On June 25th, three of 
these animals and one which had not been away showed trypano¬ 
somes, and they were all dead within a month ; one died within ten 
days, and this at the height of the dry season, when deaths are said 
not to take place. Four other animals were suspected, but did not 
then show organisms. The rest of the herd were all in good condition, 
looking bright and doing the hard agricultural work well. On July 
18th, all remaining animals were examined, and eleven, some of them 
straight from the plough, showed trypanosomes. The owner, who 
possessed a small microscope, picked out another on the 22nd, one on 
the 27th, and we found two more on the 29th. Three of these were 
cows which had not been exposed to Glossina for twelve months at 
least. 
All these animals were segregated, and those not showing 
organisms were placed by themselves in a kraal and grazing area 
which appeared free of all biting flies, such as Stomoxys and 
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