TOXINES. 19 



isolated receptors. For the hen is not absolutely proof against 

 tetanus, and it is also possible to demonstrate a slight antitoxic 

 activity in the brain, &c., of that bird. Corroborative evidence 

 of this is afforded by the fact that direct intercerebral injection 

 of tetanus poison produces the symptoms of tetanus in the hen. 



Hence, according to the views of EHRLICH and WASSERMANN, 

 the defective attraction of the toxine for the body cell (receptor) is 

 the main cause of natural antitoxic immunity. If the poison 

 circulates in the free state and does not combine with the 

 receptors, or does so only to an insignificant extent, the toxo- 

 phore group is unable to act energetically, and so no serious 

 injury is done. 



Defective attraction, however, is not invariably the cause of 

 natural immunity. Thus, MORGENROTH * found that in the case 

 of the frog tetanus poison enters into firm combination even in 

 the cold, without making the animal ill. Under these conditions 

 the toxophore group is inactive ; but it acts immediately when 

 the frog is warmed to about 30 C. 



These theories of the attraction of the poison for the living 

 cell and their specific combination are supported by experi- 

 mental proofs. WASSERMANN 2 found that fresh substance from 

 the central nervous system of susceptible animals combined with 

 considerable quantities of tetanus poison. This was in agree- 

 ment with the results of METSCHNIKOFF and ASAKAWA, who 

 found that, in the case of less susceptible animals, the smaller 

 the degree of susceptibility the less, too, was the amount of 

 combination in the brain, &c. Thus, the brain of the hen only 

 enters into feeble combination with the toxine, and that of the 

 tortoise not at all. An additional support of this theory is 

 furnished by experiments which show that, in the case of those 

 animals (e.g., rabbits) in which the tetanus poison combines intra 

 vitam with receptors which are not attached to the cells of the 

 central nervous system, emulsions of other organs e.g., the 

 spleen also combine with the tetanus poison (WASSERMANN). 



It is not a general rule that receptors only occur in the 

 particular organs in which the poison produces its injurious 

 effects. It frequently happens that combination and formation 

 of antitoxine take place in other organs where the toxine does 

 little injury. The action of the poison and formation of the 



1 Morgenroth, "Zur Kenntnis des Tetanus des Frosches," Arch. Inter- 

 nat. d. Pharmacodyn. , vii., 265, 1900. 



2 Wassermann and Takaki, " Ueber tetanusantitoxische Eigenschaften 

 des Centralnervenssystems, BerL klin. Woch., 1898, 5; Wassermann, 

 " Weitere Mitt, iiber Seitenkettenimmunitat," ibid., 1898, 209. 



