364 
PLEURO-PNEUMONIA IN AUSTRALIA. 
so slight as wholly to exclude all chance of certain notice, especially 
among bush cattle. Though we do often observe among domesticated 
cattle that high inflammatory fever sets in when the lungs are first 
attacked, still we have good reasons to believe that the active element 
has been doing its deadly work among the component parts of the 
blood long before symptoms of lung attack sets in ; and I believe that 
many of the cases 1 have dissected go a long way in demonstrating this 
fact. I am led to this inference from observing that if the blood of many 
of those animals but slightly attacked in the lungs be collected, a thin, 
milky-looking fluid gathers on its surface, which I take to be disorganized 
fibrine, and I believe fibrinous effusions take place very early in the lungs 
after they are attacked, but what may be the cause of this disintegrated 
state 1 cannot say. 
Many animals attacked with pleuro-pneumonia epizootica recover, 
that is to say, the lung or part of the lung that has become hepatized 
gets enclosed in a newly-formed membranous sac when the communi¬ 
cating powers of the disease cease, but often a suppurative cyst forms 
in the centre of the hepatized part, and, gradually spreading until it 
comes in contact with healthy tissue, pleuro-pneumonia epizootica starts 
anew. Or before this time some external cause may start the disease 
anew, and in both cases it resumes its powers of communication from 
one animal to another. The dormant period then is that between the 
cessation of the first attack and the commencement of the second. 
Looking at the spreading properties of pleuro-pneumonia epizootica, 
nearly all who have scientifically studied the malady agree in this, that 
it spreads from one animal to another by wa^s and means not clearly 
understood. 
But even if we take a glance at those we do know, it will teach us 
the amount of care needed to arrest its progress. 
We know a contagious disease needs touch; an infectious disease 
needs but be breathed; and he must either be a bold or an ignorant 
man who would stand up and assert that pleuro-pneumonia epizootica 
cannot avail itself of both tin se channels. 
It matters little how the virus is communicated, whether by the food, 
the drink, the air, the skin of another animal, or the c.othes or hands 
of a man. It matters not how you bring the virus. It may fall on 
the grass and be dried up by the burning sun. Whatever disturbs 
that grass sends the poisonous particles afloat on the wings of the wind, 
to be breathed or licked by some unfortunate beast. 
And we can go further, and speak of a healthy member of a diseased 
family communicating the malady ; and why not, if the virus should fall 
on its skin ? And if, as is sometimes the case, that animal’s constitution 
resists the attack, may it not be breathed or licked from its hide. 
Instances of disease being thus communicated are not wanting in human 
pathology, especially in the case of measles and smallpox. 
It matters little though the virus be imperceptible to the naked eye. 
The inoculating matter is so on the point of the surgeon’s lancet. 
We know, too, that inoculation will produce pleuro-pneumonia 
epizootica without even a scratch. The superficial absorbents take it 
up most keenly, though it would be difficult, without actual experiment, 
to say with certainty at what stage of the disease it is communicable. 
CAUSES. 
1st. Primary. 
2nd. Predisposing. 
3rd. Exciting. 
