186 THE MICROSCOPICAL NEWS. 
adequate to meet the demands of farmers for a supply of vaccine. 
In the space of fifteen days we have vaccinated, in the departments 
surrounding Paris, more than 20,000 sheep, and a large number of 
cattle and horses.” These results of Pasteur were afterwards con- 
firmed by independent experiment made by a commission of 
medical men at Chartres. 
Dr. Klein considers it to be established that Pasteur’s “ vaccine” 
“‘when inoculated into sheep, produces some modified form of 
splenic fever that protects the sheep against the after-production of 
fatal splenic fever when the virulent material is inoculated into 
the sheep.” He has not himself performed experiments on sheep, 
and is not acquainted with the particular details of the method by 
which Pasteur produced his “ vaccine.” Dr. Klein’s experiments 
were performed upon rodents, such as mice, guinea-pigs, and 
rabbits ; and whilst not doubting the “absolute reliability of M. 
Pasteur’s successful vaccination of sheep with the Bacillus anthracis, 
and the immunity thus conferred upon them,” his own observations. 
lead him to question the applicability of these results to anthrax in 
other animals than sheep, and to other infectious maladies. 
He cultivated these organisms in clarified soup, made from fresh 
pork ; and he found that the formation of spores, contrary to the 
results of Pasteur’s researches, was. not preventedjby exposure to: 
atmospheric oxygen, but that spores were formed only upon the 
exposed surface of the nutritive fluid, and that as long as the cells 
were grown in deep vessels (test tubes) beneath the surface no. 
spores were produced. He also found that a temperature higher 
than 43° cent. did not prevent spore formation when the cells by 
growing upwards rose into contact with the air. His experiments 
also differ from those of Pasteur in showing that when the modified 
virus is once obtained, it is not necessarily transmitted to the next 
cultivation. He states that when guinea-pigs and rabbits were in- 
oculated with the Lacllus anthracis, cultivated artificially and 
prevented from forming spores, they took the virulent form of 
anthrax, and generally died ; and that those which recovered from 
the disease did not preserve any immunity from the effects of 
subsequent inoculations. With mice it waS somewhat different. 
They were peculiarly susceptible to true anthrax ; but inoculations. 
with successive cultivations of the bacillus were decreasingly fatal 
to them as long as spores were not formed, until at last an attenuated 
form was obtained which had no ill effect. If, however, this 
attenuated or harmless bacillus was allowed to come to the surface 
of the cultivating medium and to form spores, subsequent inocula- 
tion of the same mice with this material produced typical anthrax, 
from which they died. The gradually decreasing fatality from in- 
oculations with the cultivated bacilli, when prevented from forming 
spores for many generations, was doubtless owing to the exhaustion 
