CYTOLYSINS 99 



as the result of immunization, and is hence exclusively found in 

 the immune serum. 



Ehrlich and Morgenroth confirmed these findings and succeeded 

 in demonstrating the presence of both components in the fresh serum 

 of the immunized animal. These two substances, as we have already 

 seen, are now generally spoken of as amboceptor (immune body, 

 Bordet's substance sensibilisatrice) and complement (alexin of Buchner 

 and Bordet). These discoveries were of fundamental importance, 

 as they immediately led to the recognition that the bacteriolytic 

 action of immune sera is similarly due to the coaction of two sub- 

 stances, of which the one also is present in fresh normal serum, while 

 the other only appears as the result of immunization. A proper 

 explanation was thus given for Pfeiffer's original observation, made 

 in 1894, that inactivated bacteriolytic goat serum recovers its 

 bacteriolytic action when introduced into the peritoneal cavity of 

 a guinea-pig. 



Metschnikoff and Bordet showed that the same 'result is obtained 

 by mixing such inactivated serum with fresh peritoneal fluid in vitro, 

 or by adding fresh serum or freshly defibrinated blood, the reason, 

 of course, being that under the conditions of the experiment the 

 inactivated immune serum finds the necessary complement both 

 in the fresh peritoneal fluid and the fresh blood. 



Bordet then showed that while naked eye observation of the 

 process of hemolysis suggests that the red cells undergo dissolution, 

 this is in reality not the case, but that the hemoglobin only undergoes 

 dissolution into the outer medium, and that the stromata of the 

 cells (the shadows of the red cells) can be separated by centrifugation, 

 and demonstrated as such. 



Similar observations were made regarding the action of the 

 corresponding cytotoxic sera upon ciliated epithelial cells and 

 spermatozoa. When such cells are introduced into the peritoneal 

 cavity of an animal that has been correspondingly immunized the 

 cells promptly lose their motility; but while the epithelial cells 

 gradually undergo destruction the spermatozoa remain unchanged. 



While the changes which are thus effected by cytotoxic sera in the 

 case of red cells, ciliated epithelial cells and spermatozoa are very 

 apparent, and while such cells, hence represent excellent test objects 

 for the purpose of studying the nature and mode of action of the 

 immune sera in questipn, the demc-nstration^of a rceurotoxic, hepato- 



