278 Report on the Health of Animals of the Farm. 
undertaking experiments to determine the means by which the 
disease is propagated. 
At present I hold the opinion that cohabitation appears to be 
absolutely necessary to the successful conveyance of the morbific 
matter from one animal to another in a form by which it can 
produce its specific consequences; and until the materies morbi 
of pleuro-pneumonia be conveyed from a distance, and made to 
take effect on an animal whose perfectly healthy condition could 
not be disputed, I feel justified in maintaining this opinion. It 
is to be borne in mind that this belief is the outcome of years of 
observation, and of experiments had recourse to specially to de- 
termine the question. It has been objected that the experiments 
are few, which I am ready to grant ; but I may reply, that this 
objection does not apply to inoculation with the diseased products 
of pleuro-pneumonia. Thousands upon thousands of cattle have, 
during the last twenty-four years, been thus experimented upon 
without any affection of the lungs being produced. Indeed, the 
advocates of this system base its value upon the prevention of 
pleuro-pneumonia by the introduction of the morbific matter into 
the organism of healthy cattle. No difficulty exists in conveying 
from a distance, undefined and undefinable as to extent, the 
morbific matter of cattle-plague, sheep-pox, foot-and-mouth 
disease, and of the numerous blood diseases known by dif- 
ferent local terms which are fatal to cattle ; and when the same 
thing is accomplished by experimenters with the morbid pro- 
ducts of pleuro-pneumonia, I will readily admit that my belief 
has been resting on an erroneous conclusion as to the means 
by which the malady is spread over the country. 
I may here mention some other circumstances which have 
been established of late years with regard to the extension of 
pleuro-pneumonia, which bear on what has been previously 
advanced, viz., that the malady had no existence in Australia 
until introduced in 1858 by a diseased cow from England ; nor 
in New Zealand until 1864, when some infected cattle were 
landed from Australia ; that America was free until 1847,. 
when cattle from England took the disease to New Jersey, and 
that the importer, by slaughtering his entire herd, eradicated 
the malady at that time. That America remained iYee until 
1859, when she again received the disease from Holland by 
imported cattle, and that unfortunately it then gained a footing 
in the country. Sweden is also said to have received the disease 
by infected cattle sent from England in 1847, and from thence 
it spread to Denmark. Norway likewise suffered from the 
ravages of the disease in 1860, it having been imported by a 
number of Ayrshire cattle from Scotland for breeding purposes,, 
which proved to be affected with pleuro-pneumonia. 
