ANTI-BACTERIAL SERA. Ill 



possible. The normal individual in order to utilize all the lytic 

 and possibly the opsonic anti-body in a specific serum, therefore 

 must possess large amounts of complement. Numerous investi- 

 gators, among which may be mentioned Ehrlich, Morgenroth and 

 Metchnikoff, have found that in certain diseased conditions there 

 is an actual decrease in complement. Moreover, as far as can be 

 determined, complement is not increased during disease and im- 

 munization. Richardson has shown that the serum of typhoid 

 patients is not usually able to destroy typhoid bacilli, but that 

 upon addition of fresh serum from a normal individual the typhoid 

 immune serum is able to bring about complete lysis of typhoid 

 bacilli. Numerous similar observations have been made in natural 

 infections in man. In the efficiency of ant i -bacterial sera the 

 presence of sufficient amounts of complement undoubtedly plays 

 a large part and in certain cases the lack of complement probably 

 is the cause of failure of beneficial action of certain specific anti- 

 bacterial serum. Various attempts have been made to increase 

 the amount of complement. Ant i -complement has been used 

 to immunize in order to excite the over-production of complement. 

 Injection of fresh complement with the immune serum has been 

 tried by some investigators. Efforts have been made to preserve 

 the complement in immune sera by freezing the serum and keeping 

 it cold until it is injected. Recently dried immune sera have 

 been advocated because it is known that complement is preserved 

 for a long time in serum dried down soon after it is drawn. It is 

 questionable, however, whether by any of these methods enough 

 complement will be present to activate the amount of immune 

 bodies injected. Hiss recently has published results on the cura- 

 tive action of subcutaneous and intraperitoneal injection of ex- 

 tracts of leucocytes from normal rabbits. Of this leucotic extract 

 Hiss says, "The action of the leucocytic extract may be due to 

 the enhancement of the bacteriolytic action of the animal's plasma 

 by the introduction of complement but is most likely chiefly due 

 to the poison neutralizing or destroying bodies." 



The practical application of specific ant i -bacterial sera in 

 the treatment of the various infections in man has been tried on 

 a large scale. It has been found that by the early injection of 

 serum from animals actively immunized to various organisms, 

 animals can be rendered non-susceptible to infections with pneu- 



