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 amoeba disposes of similar microorganisms which serve 

 it as 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- 

 Hlli maybe 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- 

 hlnndcd animals. Thus tlu> 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 in it. Bacillus subtilis and Bacillus mega- 



