172 
PLEURO-PNEUMONIA IN AUSTRALIA. 
plausibly supported the non-contagion theory, we are ready 
to maintain that pleuro-pneumonia is an infecto-contagious 
disease. In typhus fever, and some others, certain poisonous 
effluvia issue from diseased bodies, and are diffused through 
the air, rendering susceptible animals liable to inoculation by 
the virus. Such effluvia attach themselves to clothes, hair, 
fur, wool, cotton, or the mucous membranes of animals, and 
so communicate the contagion or infection to indeterminate 
distances. The poisonous fomites appear to be not widely 
diffused through the air, but seem to surround certain nuclei, 
the moving modus of spreading this contagion. That the 
dispersion of diseases by contagion or infection is often 
dependent on peculiar conditions of the atmosphere, no one 
can doubt; 'plus or minus indications of the earth's electricity, 
or of the air, in cholera have been found to produce great 
influences by increasing or retarding the intensity of that 
dreadful malady. That the whole series of phenomena result 
from the influences of morbific poisons on, or in the body, 
few physiologists can doubt. But whence this or these 
invisible active agents ? The mud of old Nilus may originate 
plague, and festering flats of the Ganges generate cholera. 
Yellow fever spreads in the West Indies, and intermittents 
annually occur in the marshes of the Maremma; but the 
fomitic virus, who can describe ? All we know is thus far :— 
A definite train of consequences follows the insertion ; and 
it appears that this secret power often is an agent, sui generis, 
producing disease of a definite nature and attacking only 
particular species, and particular organs. Doubtless, the 
famous Board of Health, in their report, shook the belief of 
many regarding infection and contagion, but until clearer 
facts are propounded it will be as safe to imagine that such 
means of disseminating, or spreading far and wide, do indeed 
exist, and let us guard against the serious effects. There is 
more material matter floating through the air than most 
people can conceive—light seeds of various kinds, impalpable 
solid matter in a minute, pulverised state, germs of smut, 
blight, and, perhaps, of animal diseases. “The nebulous 
dust, or sand," says Ehrenberg, “which mariners encounter 
in the vicinity of Cape De Verd Islands, 360 miles from the 
African shore, contains the remains of eighteen species of 
siliceous shelled polygastric animalcula." Men have become 
rabid from moisture off the tongue of a mad dog, and car¬ 
ried into their system by the absorbents, without any bite or 
abrasion in the flesh or skin whatever. 
Seat of the disease .—The prime seats of the disease are either 
in the lungs or in its near neighbour the pleura. So delicate 
organs as the lungs may be supposed liable to numerous dis- 
