CLIMATIC INFLUENCES OX DISEASES OF LIVE STOCK. 
717 
had been affected but had recovered. From these facts T think it 
may fairly be assumed that a time will come when the disease will 
become of so mild a nature in Australia that few, if any, deaths will 
occur from it. 
It is well known that the dry atmosphere of our Western districts 
is inimical to diseases of a pulmonary nature, and this is strongly cor- 
roborated in the case of pleuro-pneumonia and tuberculosis in cattle. 
The percentage of those cases in cattle from the West, as 
evidenced in the Brisbane slaughter-yards, is exceedingly small as 
compared vvilh coast cattle. On the other hand, some of our most 
virulent attacks of sheep catarrh have been in districts far removed 
from coastal influence. Pleuro-pneumonia and tuberculosis make 
greatest headway in a humid atmosphere. Catarrh, on the contrary, 
disappears under a similar influence. 
It is worthy of mention here that pleuro-pneumonia is more 
prevalent on basaltic soils, such as Darling Downs and Peak Downs, 
than on the Upper and Lower Cretaceous formations of the West. 
By what special agency this is brought about I am not prepared 
to say, but would imagine that, the Cretaceous formations being of a 
more saliferous character, the herbage would necessarily partake of 
the same nature, and therefore bo more invigorating. 
I think 1 am justified in deducing from the facts I have stated that 
in diseases of a pulmonary nature, such as pleuro-pneumonia, the effect 
of our climate is to diminish their intensity, while with those of a broncho- 
febrile nature, such as sheep catarrh, it has an opposite tendency. 
While arriving at these conclusions, I do not ignore the fact that 
the mitigation of pleuro-pneumonia may, to some extent, have been 
due to hereditary immunity. Indeed, I have had practical evidence of 
such a contention. In our operations for the artificial production of 
inoculation lymph, carried on during the past live years, it has been 
our frequent experience that calves, obtained from a herd in which 
pleuro-pneumonia had existed within a period of two or three years 
previously, are in many instances immune to the disease by inocula- 
tion, and I have it on the authority of many cattle-owners that they 
have had similar experience. 
Nor can we overlook the fact that some diseases lose much of 
their virulence by acclimatisation, so to speak. This is the case with 
rinderpest. In its native habitat, the steppes of Eussia, although 
constantly present, the mortality from that disease is inconsiderable, 
whereas, when introduced into iow countries and to Great Britain, its 
ravages have amounted to almost total annihilation of the infected 
herds. So with Australian catarrh. In the upland districts, in 
which it lingered for many years, notably the Monaro district of New 
South Wales and the Upper Burnett district of this colony, the annual 
losses from it were small; hut when communicated by sheep from 
those districts, and set up in fresh localities, its ravages have been 
very great. 
Those who have had practical experience in the breeding of stock 
are aware of the powerful influence exercised by the Australian 
climate in modifying the types of sheep and cattle. Is it not there- 
fore reasonable to assume that a similar influence will be exercised 
in the modification of diseases to which the same description of stock 
is liable P 
