PHENOMENA FOLLOWING IMMUNIZATION 79 



and Metchnikoff, soon after his first communication, extended his 

 phagocytic studies to phenomena of infection. His first investiga- 

 tions concerned themselves with an infectious disease caused by a 

 form of yeast in a small crustacean the daphnia or water flea. He 

 showed that recovery or death from the disease depended upon the 

 completeness with which the invading micro-organisms were taken 

 up by the white blood cells found in the body cavity of the daphnia. 

 Immediately subsequent studies, carried out with the aid of numer- 

 ous pupils, embraced an extensive material throughout the animal 

 kingdom in w T hich he attempted to show parallelism between natural 

 immunity and the phagocytic activities mobilized by the body against 

 the invading germs. 



Meanwhile studies along another path were in progress. It had 

 been observed many years before this by the physician, Hunter, that 

 the shed blood of animals was not as easily subject to putrefactive 

 change as were many other organic substances. Similar observations 

 by Traube and, in 1881, by Lord Lister 1 (the latter reported at a 

 time when Pasteur's experiments were reaping their first practical re- 

 sults) further stimulated investigation of the blood as the possible 

 seat of the increased antibacterial property. For, indeed, these 

 observations seemed to imply that by resisting decomposition, even 

 when inoculated with putrefying material, the blood must possess 

 definite means of inhibiting or even destroying the putrefactive 

 bacteria. 



In 1884, in a dissertation submitted at Dorpat, Grohman 2 stated 

 that cell-free blood plasma inhibited the growth of micro-organisms. 

 But Grohman was unable to determine actual bacterial destruction. 

 Similar, but inconclusive, observations were published by Von Fo- 

 dor 3 in 1887. In 1888, however, Nuttall, 4 who was investigating 

 the validity of the phagocytic theory of Metchnikoff, experimentally 

 determined that normal blood possessed the property of killing bac- 

 teria a property now spoken of as "bactericidal" power. The atti- 

 tude taken by Nuttall, and others of the Fliigge school, toward 

 Metchnikoff 's opinions was one of doubt as to the fundamental sig- 

 nificance of phagocytosis in determining resistance. They argued 

 that Metchnikoff had not yet proved that living bacteria were taken 

 up by the phagocytic cell, and that the action of these cells might 

 therefore be interpreted as merely a process of removal of the dead 

 bacteria, after these had been killed by other influences. Nuttall, 

 accordingly, repeated some of Metchnikoff's experiments on anthrax 

 in frogs and rabbits, essentially confirmed the basic observations, 

 but showed also that the cell-free defibrinated blood of these and 



1 Lister. Trans. Intern. Med. Congress, London, 1881. 



2 Grohman. Cited from Lubarsch, Centralbl. f. Bakt., 6, 1889. 



3 Fodor. Deutsche med. Woch., No. 34, 1887. 

 * Nuttall. Zeitschr. f. Hyg., Vol. 4, 1888. 



