272 QUEENSLAND AGRICULTURAL JOURNAL. [1 Ave., 1901. 
—the end of February, March, and April. Asa matter of fact, nothing is 
determined from this point of view ; there are as many fluctuations as are found 
in the climate of a similar zone. So that in a certain year there may be many 
ticks in March and very few in the following year at the same period, when, for 
example, the ticks only appear in May. Another observation which I have 
often verified, and which is well known to competent breeders in the Argentine, 
is the influence the direction of the wind exercises on the appearance of the 
disease, and even on its degree of virulence. It is the hot and stormy winds 
which are the most redoubtable of all. Probably the reason is, that owing to 
the heat and the atmospheric depression, the organism is in an unfavourable 
condition to resist, and hence is all the more easily assailed. 
It has been truly said that swampy districts are the most dangerous in 
respect of bovine malaria; but this disease may also exist on rich plains 
devoid of humidity. I have already pointed out that in sending cattle from 
the south towards the north, they run the greatest chance of contracting the 
disease. It is an experiment easily proved, which I have several times repeated 
in order to satisfy myself of the time necessary for the generation of the 
disease. 
In one of these experiments, I sent to the north of Santa-Fé seventeen 
head of cattle raised in the southern region free from malaria. 
When they arrived on 18th April, in the infected zone, the first case was 
observed on 5th May—i.e., seventeen days after their introduction into the 
contaminated country. They were all taken ill, one after the other; and of the 
whole number eight died. 
On the other hand, animals which travel from north to south remain in 
health. 
Nevertheless, if they carry ticks with them, they may contaminate the 
‘Southern cattle which were free till their arrival. I say “they may,” because 
this contamination is not fatal. To be so, the ticks must find conditions 
favourable to their evolution, otherwise they die on the spot, or only give rise 
to a degenerated offspring destined to quickly die out. 
It is just these particular circumstances which have saved southern 
Argentina from the scourge, and, in particular, the large and rich province of 
Buenos Ayres. 
Indeed, no precautions have been taken in the transport of tick-infested 
beasts coming from the north, either for export or for being fattened on the 
richer pastures of the south. And yet, so far, no new centres of malaria 
have been observed. 
On this matter I made, during a favourable season, a decisive experiment. 
I had received eight head of cattle from the north of Santa Fé and two from 
Missiones—badly infected districts All these animals, covered with ticks, were 
placed in a field about 200 metres square, a field quite free from malaria, 
covered with small, fine grass, with fifteen southern cattle, of which several 
bulls were cross-bred Durhams, anemic, and consequently eminently predisposed 
«to disease. 
These animals lived together for eighty-nine days withouta single one 
showing the least symptom of disease. The blood was often examined and 
the corpuscles were counted, without finding anything abnormal. On the skin 
it was impossible to find a single tick ; it is therefore evident that in this field 
they had met with a serious obstacle to their development. Several of these 
southern animals which had served for this experiment, when inoculated later 
on with blood of diseased animals, contracted the malaria properly. 
Tt is a curious thing, but one can create artificially, in a thoroughly infested 
country, fields free from the disease. 
Thus, the substitution of lucerne for the natural grass, at the same time 
that it constitutes an improvement from an agricultural point of view, creates 
also a centre free from malaria. 
The reason is, that lucerne is so distasteful to ticks, that their multiplica- 
tion is impossible. There are to-day, in the Argentine Republic, immense areas 
eee Ss 
