XII. 
ACTION OF BLOOD SERUM AND OTHER ORGANIC 
LIQUIDS. 
Blood Serum.—Bacteriologists have long been aware of the fact 
that many species of bacteria, when injected into the circulation of a 
living animal, soon disappear from the blood, and that the blood of 
such an animal a few hours after an injection of putrefactive bacte- 
ria, for example, does not contain living bacteria capable of develop- 
ing in a suitable nutrient medium. Wyssokowitsch, in an extended 
series of experiments, has shown that non-pathogenic bacteria in- 
jected into the circulation may be obtained in cultures from the liver, 
spleen, kidneys, and bone marrow after they have disappeared from 
the blood, but that, as a rule, those present in these organs have lost 
their vitality, as shown by culture experiments, in a period varying 
from a few hours to two or three days. According to the theory of . 
Metschnikoff, this destruction of bacteria in the blood and tissues of a 
living animal is effected by the cellular elements, and especially by 
the leucocytes, which pick up and digest these vegetable cells very 
much as an amceba disposes of similar microérganisms which serve 
itas food. Some such theory seemed necessary to account for the 
disappearance of bacteria from the blood before the demonstration 
was made that the serum of the circulating fluid, quite indepen- 
dently of its cellular elements, possesses very decided germicidal 
power. 
Von Fodor first (1887) called attention to the fact that anthrax ba- 
cilli may be destroyed by freshly drawn blood ; and Nuttall (1888), 
in an extended series of experiments, showed that various bacteria 
are destroyed within a short time by the fresh blood of warm- 
blooded animals. Thus the anthrax bacillus in rabbit’s blood was 
usually killed in from two to four hours when the temperature was 
maintained at 37°-38° C., and the same result was obtained with 
pigeon’s blood at 41° C. But when the blood was allowed to stand 
for a considerable time, or was heated for forty-five minutes to 
45° C., it served as a culture fluid, and an abundant development of 
anthrax bacilli occurred init. Bacillus subtilis and Bacillus mega- 
