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1 Ave., 1901.] QUEENSLAND AGRICULTURAL JOURNAL. 275 
South, where the disease is unknown, and a mixed zone of which the principal 
nucleus is the rich district of Rosario, where lucerne fields form widely-extended 
immune localities in the midst of the infected regions. 
The lines which I have indicated on my map as limiting the homes of 
infestation are necessarily slightly imaginative, since in order to satisfy myself 
personally of their absolute exactness, I should have required several years of 
exploration. 
Now that we know the bovine malaria better, it will be easier to determine 
the exact geographical area of this disease. Meanwhile, the indications 
recorded on my map give a sufficiently good idea of the dangerous regions.* 
THE IMPORTANCE OF THE BOVINE MALARIA FROM THE 
BREEDING POINT OF VIEW. 
According to locality, bovine malaria has a variable importance. As a 
matter of fact, it is the northern districts -that is to say, those in which the 
disease is endemic, which suffer least from it. Indeed, on a large number of 
properties, the disease is not even known, because on these they raise only the 
criollo (native) cattle, and we are aware that under these conditions, the young 
ealves are naturally vaccinated by the ticks. Still, one occasionally sees, even 
amongst these herds, epidemics of malaria more or less fatal. : 
But, in order to compete in foreign markets, to produce a return which 
shall harmonise better with the greater cost of keep and location, it is necessary 
to breed animals of prime quality, which are got b¥ importation of the blood of 
celebrated breeds, notably the Durham and the Hereford. 
It is when these well-bred animals are introduced into the infested districts 
that the whole gravity of the malaria is felt. The further one goes from the 
north, the more difficult and the more costly becomes the improvement in the 
cattle. There are some districts in which the mortality amongst imported 
cattle ranges from 50 to 6O and 80 per cent. There are even cases in 
which it has reached 100 per cent. 1 know an extensive breeder to the 
north of Santa Fé who, after fifteen or twenty years of unheard-of efforts, 
succeeded in acclimatising on his station several fine-bred bulls. To arrive at 
this result, he assured me he had lost more than 1,000,000 franes (over £40,000) 
in imported breeding cattle which died of malaria. 
Thus, it is in the difficulty of improving stock in the infested district that 
the seriousness of malarial disease lies, and it is just the most progressive cattle- 
‘owners who pay the heaviest tribute to the disease. In the mixed zone, wheré 
the land is not swampy, there are splendid plains suited to the perfect and 
rapid fattening of cattle, and the southern proprietor reaching this limit often 
suffers enormous losses in consequence of the malaria. 
We have seen how Nature opposes the invasion of bovine malaria. Yet, 
at the same time, there is always the dread of the progressive adaptation of the 
ticks to the immune districts. In the same way as microbes become accustomed 
to encroach little by little upon media at first unsuitable to them, so the ticks 
may, in the limiting zone, accustom themselves to thrive in climatic conditions 
formerly inimical to them. 
Bovine malaria always constitutes a danger for localities to which the 
ticks may be transported alive and where they will find a location suitable for 
their sata On the other hand, there is no need to exaggerate the 
danger. Thus, for Burope, or for any country which demands a voyage of twenty- 
five or thirty days, the transmission of the malaria need not be feared, since on 
arrival, the ticks will have fallen off, leaving the animals free from the parasite, 
which is the only efficacious medium between the hematozoa and the cattle.t 
* With the aid of the information which I have obtained, and the numerous examinations 
of blood sent from different parts of the Republic of Uruguay, I have been able to prolong 
approximately the lines delimiting the infested zones, from the Argentine to Uruguay. 
+ The eggs, which might preserve the species for some time, are not hatched out on the 
animal, but on the ground, as we have seen. 
(Lo be continued.) 
