MICRO-ORGANISMS. ~- 155 
rollers, which are made to revolve. The bacteria adhere to 
the rollers, and are thus subjected to a crushing process for 
some time. The powder, consisting of crushed and entire 
cells, is brushed or s¢raped off the rollers, and kept until a 
sufficient quantity has been obtained. The crushing is done 
inside a closely fitting glass case, in the sides of which are 
_fixed rubber sleeves and gloves for the manipulator, who by 
their aid is enabled to remove the powder, and attach a 
culture, without opening the case, excepting at the beginning 
and end of the process. When enough has been prepared, 
the powder is mixed with water, and centrifuged until there 
is obtained a clear supernatant liquid above a slimy deposit. 
This liquid is akin to the old tuberculin. The slimy deposit 
is dried, ground as before, and centrifuged. The clear super 
natant liquid of this centrifuging is the first portion of 
Tuberculin T.R., and contains only the endocellular pro- 
ducts. The process is repeated with the deposit, and the 
clear fluid is added to the first portion of 7.2. When the 
deposit contains nothing but a débris of cotton-wool, &c., the 
operation is finished. and all the centrifuged fluids are mixed 
together. and, with the addition of 20 per cent. glycerine, 
form the pure toxine. An immunising property has been 
claimed for this preparation, but it does not appear to have 
been corroborated, and it has been denied. 
* 
Vacemes, Prophylactics, and Protective Sera. 
Anthrax vaccine is simply a culture of anthrax bacteria. 
Two vaccines are generally employed, the first consisting of 
a culture of bacteria which have been weakened in their 
virulence by heat, the second contaiming virulent bacteria. 
The weakened culture is first inoculated, and, when the 
animal has become partly immune, the virulent culture is 
injected, to complete the immunising process. Instead of 
using two vaccines, it seems reasonable to suppose that a 
single vaccine, which is just on the safe side of virulence, 
might ba employed. A single anthrax vaccine (a secret 
preparation) is used in Australia, and in the United States 
a single vaccine has been used for “ black-leg’’ with success. 
Plague prophylactic is a broth culture of Bacterium pestis, 
i which the bacteria have been killed by an exposure to 
70° C. The prophylactic is preserved by the addition of 
a half per cent. of carbolic acid. It is, therefore, a suspen- 
sion of dead bacteria in a solution of bacterial toxine, both 
of which constituents have immunising properties. 
The various protective and antitoxic sera are obtained by 
injecting first weakened and then virulent bacteria,in gradu- 
