392 ON THE RELATIONS OF MICRO-ORGANISMS TO DISEASE 
effected by M. Pasteur. By cultivating this bacterium in a particular manner, 
which he has not yet published,’ he enfeebles the organism, as he believes, and 
produces such an alteration in it that, when inoculated into a healthy fowl, 
it produces only a modified, and no longer fatal form of the complaint ; but 
the bird is thereby rendered secure against taking the ordinary form of the 
disease. It has been really vaccinated, if we adopt M. Pasteur’s extension of 
the term vaccination to other similar cases; for just as we speak of an iron 
milestone, we may, if we please, apply the term vaccination to the use of a virus 
other than the vaccine obtained from a heifer. But though the vaccination 
with the modified bacteria of the fowl-cholera does not occasion the fatal disease, 
it produces pretty severe local effects. If inoculated on the breast of the fowl, 
it causes a limited gangrene of the pectoral muscle, the affected part falling 
off in due time as a dry slough. Through the great kindness of M. Pasteur, 
I have now the opportunity of showing to the Section a hen which has been 
treated in this way. You observe a slough on the breast of the bird about as 
Yarge as a penny piece; it is dry, and obviously old. The fowl has been some 
days in my possession subsequently to its journey from Paris; but though 
more than enough time has elapsed since the inoculation to have caused its 
death, had the disease been in the ordinary form, it is, you see, in good health, 
bright and active, and it both eats and sleeps well.” 
I will now return to the Bacillus anthracis, with regard to which I shall 
have again to refer to the labours of M. Toussaint. First, however, I must 
allude to the work of some of my own countrymen. In March 1878, an experi- 
ment was made at the Brown Institution, at the suggestion of Dr. Burdon 
Sanderson, of inoculating a calf with the blood of a guinea-pig which had died 
of splenic fever, which is exceedingly fatal to rodentia. The result was that the 
calf took the disease, but in a mild form, and recovered from it; and a similar 
fact was observed in two heifers treated in the same way.?* 
This line of inquiry has since been followed up by Dr. Sanderson’s successor 
at the Brown Institution, Dr. Greenfield, with a view of ascertaining whether 
the milder form of the disease in cattle, resulting from inoculation with the 
blood of rodentia affected with it, confers upon the cattle immunity from the 
complaint in its fatal form; or, to use again M. Pasteur’s expression, whether 
the cattle have been vaccinated with reference to anthrax. And I have great 
pleasure in being able to inform the Section, by Dr. Greenfield’s permission, 
* For an account of M. Pasteur’s method of procedure see the notes at the end of this address. 
* M. Pasteur’s researches on this subject are related in the Comptes Rendus de l’ Academie des Sciences, 
February, April, and May, 1880. 
* See ‘ Report on Experiments on Anthrax’, by Dr. Sanderson (Journal of the Royal Agricultural 
Society of England, vol. xvi, s.s., part i). 
