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i Ave., 1901.] QUEENSLAND AGRICULTURAL JOURNAL. 273 
sown with lucerne. I have seen lucerne fields of 83 leagues square (nearly 
10 miles square = 100 square miles) belonging to one man. In these fields the 
cattle are born and grow up without having malaria, whilst in the surrounding 
country the disease claimed numbers of victims. 
Unfortunately, on entering or leaving these lucerne fields to travel cattle 
either north or south, infested country has to be crossed, where the animals gather 
the ticks, which transmit the fever to them. These tick-infested cattle may 
again be taken to the lucerne fields and there become sick, but they do not 
create a home of infection, the ticks dying at once. All the mixed region 
(Plate XVI.) is admirably suited for these lucerne fields, of which its pastures 
are in great part composed. 
It is quite different if tick-infested animals run in natural prairies covered 
with native grasses (pasto fuerte). Under these conditions the ticks multiply 
and transform the whole prairie into one vast home of malaria. I have 
several times observed cases of this nature. 
All these observations demonstrate the danger of travelling cattle on foot 
in infested zones, especially at certain seasons of the year, as we have 
already seen. 
On the map at the end of this work I have placed an, itinerary 
representing the journey of a herd of good crossbred Durhams, sold on 1st 
March, 1899, from a property at Las Rosas, where there are vast lucerne 
fields. This herd was divided into three lots, bought by different proprietors. 
The first, composed of ninety animals, was sent towards Juarez Celman, 
on a farm situated 85 kilometres further south. The journey lasted four 
days, during which the herd crossed some infested fields. On the twelfth day 
after arrival at Juarez Celman, one cow fell sick, quickly followed by many 
others in succession; there were eighteen deaths. ‘These tick-infested animals, 
placed in artificial fields, did not create centres of infection; the disease 
claimed only those eighteen victims. 
The second lot, comprising 700 bulls and cows, left San Rosas on 8rd March 
for Constanza, a village 225 kilometers to the north. On the seventeenth day 
after they left, some of them became sick. On the following days the number 
of sick increased, and many died. On 25th March the herd was in a 
deplorable condition. It arrived at Amelia, and had only three or four days 
more to travel. When I arrived I found, some kilometres from Amelia, about 
fifty carcasses covered with ticks. The autopsy and the microscopical examina- 
tion left no doubt as to the nature of the epidemic. When the herd arrived at 
its destination the disease had claimed 220 victims. The fields of Constanza 
are especially composed of natural grasses, where the tick finds the best 
conditions for its multiplication, and the disease attacked even the cattle 
already there before the arrival of the infected herd. 
Finally, the third lot, comprising only fifty very fine cows, were to travel 
to San Justo, situated 200 kilometers north of Las Rosas. The owner, who 
had large experience of the malaria, was careful to leave his beasts at Las 
Rosas from 1st March (the date of purchase) to 12th April, awaiting the end of 
the hot weather. During this period none of the animals sickened. Then the 
cows were sent by train to San Justo, where they arrived on 18th April. From 
the railway station to the property is a distance of about 40 kilometres, which 
are travelled on foot in two days. | 
Up to the 28th April all the cows were in good condition. They grazed 
alternately in the lucerne fields and in the natural prairie where the tick 
multiplies. On the 28th April six of the cows became ill; on the 30th two 
died; on 1st May, ten died; on 2nd May, five; on the 8rd, three; on the 4th, 5th, 
and 6th, one died each day. I performed the autopsy on the two last cases of 
malaria. 
In all, twenty-six of these cows died, or 51 per cent., which, considering 
the locality, is not a very bad result. Indeed, it is no rare thing to find 60, 
70, 80, and 90 per cent. of animals dying of malaria when travelled north. 
