24 LECTURES ON IMMUNITY 



nating power of ricin on erythrocytes. On the other hand, 

 the centrifugated rabbit-erythrocytes contained an excess 

 of the nerve poison in ricin; for when they were haemolysed 

 by the addition of pure water they gave a poisonous solu- 

 tion, which injected into guinea-pigs produced death. In 

 this case we have two different poisons, the haemolytic and 

 the nerve poison in the ricin and the corresponding two 

 antibodies in the antiricin. The experiment shows us that 

 both of these poisons are bound to their respective anti- 

 bodies by means of reversible chemical processes. 



Another experiment of Wassermann and Bruck 1 may be 

 explained in a similar way. They injected an innocuous 

 mixture of the nerve poison tetanospasmin (which together 

 with the haemolytic tetanolysin is produced by the Bacillus 

 tetani in bouillon medium) and its antitoxin into the hind 

 limb of a guinea-pig. This animal showed no symptoms 

 of tetanus. But if the animal had previously received a 

 local injection of adrenalin, it was killed by the injection. 

 As H. Meyer and Ransom have shown, the antitoxin is 

 chiefly absorbed by the vascular system, the tetanospasmin 

 by the nerves. The adrenalin contracts the vessels and 

 thus hinders the absorption of the antitoxin, but it has no 

 effect on the nervous system, so that the tetanospasmin 

 may execute its disastrous effect. Hence the experiment 

 showed that the innocuous mixture contained free toxin, 

 but we are not quite certain in this case that the poison 

 and its antidote had had sufficient time to fully combine. 



The simplest way to separate toxins from antitoxins in 

 mixtures is by the aid of diffusion. Toxins as well as anti- 

 toxins diffuse in water or in gel, but the toxins generally 



1 Wassermann and Bruck: Deutsche med. Wochenschrift, No. 2 (1904). 



