from an Agricultural and Veterinary Point of View. 115 
microbes. Many of these appear to produce, in their cultivating 
media, matters which possess the property of hindering their own 
development. Since 1880, Pasteur had been making researches 
Avith the view to establish the fact that the fowl-cholera 
microbe produces its own poison. He has not yet been able 
to demonstrate the presence of this matter, but he thinks this 
can be done by using pure carbonic acid gas. The microbe of 
swine-plague is cultivable in very diverse kinds of infusions, 
but its increase in weight is so small, and it is so promptly 
arrested in its proportion, that it does seem that something is 
elaborated which stops the growth of the organism, whether 
cultivated in air or in a vacuum. Professor Raulin, in 1870, 
announced that the mould — Asperc/illus niger, when vegetating, 
develops a substance which partially checks its growth, should 
the nutritive medium not contain iron salts. It may be, there- 
fore, that the rabific virus contains two distinct substances — one 
being living and capable of multiplying in the nervous system ; 
and the other, non-vital, having the faculty, when in certain 
proportion, of interrupting the development of the first. 
Thus far I have attempted to trace, though feebly, I fear, the 
progress made by Pasteur, in his noble endeavour to benefit 
mankind, by devoting his body and mind incessantly to the 
study of part of a subsection of the organic world, consisting of 
organisms which, if infinitely mean in their dimensions, are yet 
amazingly powerful in their action, and of which little, if any- 
thing, was known before his advent. The record of his labours, 
and the success attending them, should be sufficient to stamp 
him as one of the great benefactors of the human race ; his last 
achievement as far transcending his previous victories, as his 
whole work must raise him above those, whose one or two 
discoveries have conferred immortality upon them. Though 
quietly and unostentatiously toiling for so many years without 
seeking for fame or reward, overtaxing health and strength, 
and incurring grave risks of infection from the poisons which 
he sought to render tractable and useful, as well as encoun- 
tering disparagement, incredulity, and opposition, he has never- 
theless risen to the highest pinnacle of greatness, and France has 
generously acknowledged how much he has added to her honour 
and her well-being. 
Professor Huxley, some time ago, in alluding to the benefits 
which have resulted from his labours, and pointing out the 
manner in which he has opened out such sources of wealth to 
industry and agriculture in his own country alone, has said : 
*' Pasteur's discoveries suffice, of themselves, to cover the indem- 
nity of five milliards of francs paid by France to Germany." 
But his discoveries in contagious diseases and their prevention, 
I 2 
