102 
Pasteur and his Work, 
The disease is of the nature of, if not identical with, anthrax ; 
and the Pasteurian inoculation would, it may safely be predicted, 
protect all the South African horses in the places where they 
would perish wholesale, if exposed. 
In an immense empire like our own, the greater portion of 
which is agricultural, and nearly every part of which is haunted 
and harassed by contagious diseases among the animals useful 
to man, and so essential to his welfare, this method of guarding 
against disorders which are generally fatal, and rarely amenable 
to medical treatment, should have wide and most beneficial 
application, and especially when it can be resorted to for all 
of these maladies. 
But to return to Pasteur's researches in anthrax. 
Still pursuing his investigations with regard to that disease, 
and fowl-cholera, and having subdued the virulence or microbe of 
these to his will, bringing them down to a point where they could 
not multiply in the bodies of animals inoculated with them, and 
still keeping these organisms alive in suitable media, he demon- 
strated that these now non-virulent microbes could be restored 
to their pristine activity, and rendered capable of living and 
multiplying in the blood of animals. An attenuated anthrax 
virus which would not affect a guinea-pig even a week old, 
will yet kill one just born, or one or two days' old ; and if 
some of the blood of this is inoculated into an older one, this also 
will perish ; while should the blood of this, again, be injected into 
a still older one, this will succumb ; and so on through a series, 
until at length the blood has acquired such power that the old 
guinea-pigs, sheep, and finally oxen, are unable to resist the 
smallest drop of it. It is the same with fowl-cholera. The 
most attenuated and harmless cultivation of the microbe can be 
made as deadly as ever, by passing it successively through small 
birds and chicken, until it is capable of destroying full-grown 
poultry. 
The attenuation of the poison of contagious diseases by the 
air, suggested to Pasteur the possibility of the great epidemics 
of mankind (and for that matter also, the epizootic diseases of 
animals), being modified or extinguished, and reappear or become 
more intense, through the same agency. " The accounts which I 
have read of the spontaneous appearance of the plague in Ben- 
ghazi in 1856 and 1858," he says, "tend to prove that this out- 
break could not be traced to any original contagion. Let us 
suppose, guided by the facts now known to us, that the plague, a 
malignant disease peculiar to certain countries, has germs of long 
duration. In all these countries its attenuated virus must exist, 
ready to resume its active form whenever the conditions of 
climate, of famine, or of misery present themselves afresh. The 
