114 Immunity 



pericardial fluid and tlie aqueous humor of the eye, which were also 

 found to possess bactericidal powers. 



The matter was next taken up by Buchner and his associates,* 

 who showed that the blood-plasma and blood-serum possessed 

 exactly the same bactericidal effects as the total blood. Buchner and 

 Nuttall both showed that the exposure of "the bactericidal fluid 

 to a temperature of s6°C. for a few hours entirely destroyed their 

 activity, though low temperatures were without effect upon them. , 

 Buchner found that the exposure of the serum to sunlight and oxygen 

 also destroyed the bactericidal power. ■ Neutralization of alkaline 

 serum did not destroy its activity, but when the serum was dialyzed 

 and the NaCl removed from it, the germicidal power was lost, to 

 return again when it was restored. Buchner called the bactericidal 

 principle alexin. 



Morof showed that alexin was proportionally more active in 

 sucking infants than in adults, and Ehrlich and Brieger| found that 

 it passed from mother to offspring in the milk. 



At first Buchner regarded alexin as an albumin, but later§ he 

 came to look upon it as a proteolytic enzyme, this view no doubt 

 resulting from an endeavor to explain the relation of alexin to im- 

 munity against intoxication, in which it was necessary to show that 

 alexin not only killed bacteria, but also destroyed toxins. 



Hankinjl endeavored to show that there were differences between 

 the substances destroying the bacteria and those acting upon their 

 toxic products. To the whole group he applied the term defensive 

 proteins. Those present in natural immunity he called sozins, 

 those found in acquired immunity phylaxins. Sozins with bacterid 

 cidal activity he further described as mycosozins, those with toxin- 

 destroying activities as toxosozins. Phylaxins with bactericidal 

 action were called my co phylaxins; those with toxin-destroying 

 properties toxo phylaxins. 



Metchnikoff found it unnecessary to modify his ideas, but 

 persisted in referring all the phenomena to the phagocytes or to 

 enzymes derived from them. 



At this point it will be evident to the reader that the phagocytic 

 theory and the humoral theory contain indubitable evidence that 

 both the body cells and humors are important factors in defending 

 the body against invading organisms, and that in each we see mechan- 

 isms operative in certain cases. But we have seen that both 

 Metchnikoff and Buchner are obliged to strain a point in order to 

 meet the requirement of increasing knowledge to the subject of 

 immunity. 



* "Centralbl. f. Bakt.," etc., 1889, Bd. v, 817; vi, i; "Archiv fiir Hygiene," 

 1891, X, S. 727; "Centralbl. f. Bakt.," etc., 1890, VII, 76. 

 t " Jahresb. f. Kinderheilkunde," v, 396. 

 t "Zeitschrift fur Hyg.," 1893, XIII, 336. 

 " 'Miinch. med. Woch.," 1899. 

 'Centralbl. f. Bakt.," etc., xii, Nos. 22, 23; xrv, No. 25. 



