ACTION OF BLOOD SERUM AND OTHER ORGANIC LIQUIDS. 209 
therium were also destroyed in two hours by fresh rabbit’s blood, 
but it was without action on Staphylococcus pyogenes aureus, which 
at a temperature of 37.5° C. was found to have increased in num- 
bers at the end of two hours. Further researches by Nissen and 
Behring show that there is a wide difference in the blood of dif- 
ferent animals as to germicidal power, and that certain bacteria 
are promptly destroyed, while other species are simply restrained for 
a time in their development or are not affected. Thus Nissen found 
that the cholera spirillum, the bacillus of anthrax, the bacillus of 
typhoid fever, and Friedlander’s pneumococcus were killed, while 
Staphylococcus pyogenes aureus and albus, the streptococcus of ery- 
sipelas, the bacillus of fowl cholera, the bacillus of rothlauf, and 
Proteus hominis were able to multiply in rabbit’s blood after having 
been restrained for a short time in their development. In the case 
of the cholera spirillum a period of ten to forty minutes sufficed for 
the complete destruction of a limited number, but when the number 
exceeded 1,200,000 per cubic centimetre they were no longer de- 
stroyed with certainty, and after five hours an increase occurred. 
The anthrax bacillus was commonly destroyed within twenty minutes 
and the typhoid bacillus at the end of two hours. In the experi- 
ments of Bearing and Nissen it was found that the most pronounced 
germicidal effect upon the anthrax bacillus was obtained from the 
blood of the rat, an animal which has a natural immunity against 
anthrax ; while the blood of the guinea-pig, a very susceptible ani- 
mal, had no restraining effect and served as a favorable culture 
medium for the anthrax bacillus. And the remarkable fact was de- 
monstrated that when the blood of a rat was added to the blood of 
the guinea-pig in the proportion of 1:8, it exercised a decided re- 
straining influence upon the growth of the anthrax bacillus. Later 
researches have shown that cultivation in the blood of an immune 
animal causes an attenuation of the virulence of an anthrax cul- 
ture (Ogata and Jasuhara) ; and also that the injection of the blood 
of a frog or rat—naturally immune—into a susceptible animal which 
has been inoculated with a virulent culture of the anthrax bacillus, 
will prevent the death of the inoculated animal. 
Buchner has shown that the germicidal power of the blood of 
dogs and rabbits does not depend upon the presence of the cellular 
elements, but is present in clear serum which has been allowed to 
separate from the clot inacool place. Exposure for an hour to a 
temperature of 55° C. destroys the germicidal action of serum as 
well as of blood ; the same effect is produced by heating to 52° C. for 
six hours or to 45.6° C. for twenty hours. The germicidal power 
of blood serum is not destroyed by freezing and thawing, but is 
lost after it has been kept for some time. Buchner’s experiments led 
14 
