80 INFECTION AND RESISTANCE 



other animals possessed definite bacteria-destroying properties (bac- 

 tericidal power) for many different micro-organisms. He detected 

 similar properties in pleural exudates, pericardial fluids, and aqueous 

 humor, and determined that this property was "inactivated" or de- 

 stroyed when the fluids were heated to 55 C. for 10 minutes or 

 longer. Buchner 5 then confirmed Nutt all's results and showed 

 further that the bactericidal property resided, not only in defibri- 

 nated blood, peptone blood, and plasma, but was present also in the 

 serum obtained after clotting. He applied the term "Alexin" to this 

 active constituent of the blood likening its action to that of a 

 ferment. 



The immediate theoretical result of these discoveries was an at- 

 tempt, begun by Fliigge's school, to base natural as well as acquired 

 resistance upon the bactericidal properties of the blood and body 

 fluids in general. For the observations of Nuttall and Buchner were 

 soon extended to peritoneal and other exudates by Stern, 6 and to 

 ascitic fluids by Prudden. 7 By these two groups, that of Fliigge- 

 Nuttall-Buchner on the one hand, and that of Metchnikoff on the 

 other, there were founded the two schools of immunity the humoral 

 and the cellular, both originating in attempts to explain natural 

 immunity, and later extending to problems of acquired resistance. 

 And it is to the diligent and ingenious intellectual and experimental 

 conflict between these schools that we owe much of the knowledge we 

 now possess concerning the phenomena of immunity. A bridge be- 

 tween them was early established when Buchner himself (even 

 before Metchnikoff) suggested the possible leukocytic origin of the 

 bactericidal serum constituent (alexin). The later work of Denys, 

 of Gruber and Futaki, of Wright, of Neufeld, of Bail, and of others 

 has demonstrated, as was to be expected, the inadequacy of either 

 point of view by itself, and the intimate interdependence of the 

 humoral and the cellular processes. 



As concerns the relation of bactericidal serum effects and natural 

 immunity, it could be unquestionably shown by Nuttall, Buchner, 

 Nissen, 8 and their immediate followers that the blood of most ani- 

 mals possessed bactericidal properties against many micro-organisms, 

 their experiments being so planned that the participation of leuko- 

 cytes could be absolutely excluded. However, a parallelism between 

 bactericidal power and the degree of natural resistance could not 

 be established. Lubarsch, 9 writing during the early periods of the 

 controversy, stated that "he would regard the (purely humoral) 10 



5 Buchner. Centralbl f. BaU., 1889. 



6 Stern. Zeitschr. f. klin. Med., Vol. 18 (cited from Hahn). 



7 Prudden. Med. Eec., Jan., 1890. 



8 Nissen. Zeitschr. f. Hyg., Vol. 6. 



9 Lubarsch. Centralbl. f. Bakt., Vol. 6, 1889. 



10 Bracketed phrase our own. 



