46 



JOURNAL AND PROCEEDINGS 



us take some of his blood serum and mix it with some typhoid 

 germs. We find they are immediately destroyed. Now let us 

 heat this serum to say 55° C. and repeat our experiment and we 

 find our typhoid bacilli remain unharmed. To this inert heated 

 serum let us now add a little fresh serum from the blood of almost 

 any animal, whether immunized against typhoid or not, and once 

 again the germs are immediately destroyed. 



We see, therefore, that our bactericidal or antibacterial sub- 

 stance is a complex material, part of which — the complement — is 

 destroyed by heat at 55° C, but which can be replaced from the 

 serum of almost any animal ; and another part — the amboceptor — 

 which withstands heat at 55° C, and which is found only in the 

 serum of those animals immunized against the special disease. 



Neither amboceptor alone, nor complement alone, can destroy 

 the invaders. Each is required to complete the action of the 

 other. Moreover, they have a definite mode of attack. The am- 

 boceptor attacks the organism first, and thus prepares it for the at- 

 tack of the complement, by which it is killed and dissolved. 



When germs invade the system, they 

 attack the body cells through the ambo- 

 ceptors and complement, and, if not im- 

 mediately destroyed, the cells are stimu- 

 ulated to a great overproduction of ambo- 

 ceptors and complement, which are 

 thrown off into the circulation as the bactericidal substance. 



/. Germ 



2. Amboceptor 



?. Complement 



These 



Germ 



S3 <] 



A mboceptor thrown Complement 

 from Body Cell thrown off 



fi om Body 

 Cfll 



63<D ^113 



Germ Sensitized by the Ambocep- 

 tor and ready for the Com- 

 plement 



Completnent attacking and 

 destroying the Sensitized 

 Germ 



over-produced amboceptors and complement remaining in the cir- 

 culation after the attack has subsided, produce the immunity 



