IMMUNITY. 



187 



which it contains is not destroyed, but its zymotoxic group 

 alone is destroyed; the haptophore group, on the other hand, 

 resists heat. So if heated complement be added to inactivated 

 lysin, it unites with the freed haptophore. A lysin inactivated 

 by heat with fresh' serum added disintegrates homologous cells; 

 but a lysin inactivated by heat when heated fresh serum is added 

 will not only not produce lysis of homologous cells, but will not 

 do so even when unheated fresh serum is subsequently added. 



Fig. So. — Receptor oe the Third Order, and oe Some Substance Unit- 

 ing WITH One op Them. — {Journal of the American Medical Association. 

 1905. P. 1369.) 



c. Cell receptor of the third order — an amboceptor, e. One of the hapto- 

 phores of the amboceptor, with which some food substance or product of 

 bacterial disintegration (/) may unite, g. The other haptophore of the 

 amboceptor with which complement may unite, k. Complement, h. 

 The haptophore. z. The zymotoxic group of complements. 



The behavior of mixtures of toxins and antitoxins is most peculiar, for they 

 do not in all cases obey the simple rule of relative proportion. It is true that 

 if a certain amount of antitoxin neutralizes a certain amount of toxin, then 

 any multiple of this amount of antitoxin will neutralize the same multiple of 

 toxin if the two are mixed all at once. So far the rule is simple. But if 100 doses 

 of toxin — i. e., enough to kill 100 guinea-pigs — is exactly neutralized, and then the 

 amount of free toxin necessary to kill a guinea-pig is added, it will not kill a. 

 guinea-pig as would be expected. Many doses have to be added, sometimes as 

 much as thirty or forty doses or more, before the mixture again becomes poisonous. 



