THe MicroscopicaL Nrws 
AND 
NORTHERN MICROSCOPIST. 
No. 31. OLY. 1883. 
ree. BAe TE Rep Ace a: 
By W. Biacksurn, F.R.M.S. 
(Continued from page 170.) 
R. Klein’s chief aim, in prosecuting a series of culture experi- 
ments on these micro-organisms, was to ascertain whether the 
Bacillus subtilis, of hay infusion, undergoes any change, morpho- 
logical or physiological, when artificially cultivated, and whether an 
innocuous saprophyte is capable of assuming the properties of a 
pathogenic organism. Prof. von Nageli and Dr. H. Buchner 
believed that their experiments proved this to be the case, and that 
they had also shown the converse proposition to be true, by con- 
verting the pathogenic bacillus of anthrax, or splenic fever, into 
another, identical with the harmless saprophyte of infused hay. 
In Pasteur’s researches on the Aactllus anthracis of sheep, he 
found that that organism was deprived of its contagious virulence 
when it had lost its power of producing spores, and was compelled 
to multiply itself only by the process of fission ; and this object 
was attained by cultivating the bacillus in nutritive fluids, at a 
higher temperature than 42° to 43° centigrade and exposed to the 
oxygen of the air. By this means he produced an “ attenuated 
form” of bacillus which he used as a modified wras for the pro- 
tective inoculation of sheep, just as we use vaccine lymph as a 
protection against smallpox. Pasteur gave a public demonstration 
of the results of his system of inoculation, at Pouilly-le-Fort, near 
Melun, and in his paper on “Animal Inoculation” he thus 
describes the proceeding : “‘ Fifty sheep were placed at my dispost- 
tion, of which twenty-five were vaccinated, and the remaining 
twenty-five underwent no treatment. A fortnight afterwards the 
fifty sheep were inoculated with a most virulent anthracoid mic- 
robe. The twenty-five vaccinated sheep resisted the infection ; the 
twenty-five unvaccinated died of splenic fever within fifty hours. 
Since that time the capabilities of my laboratory have been in- 
VOL. III. 
