THEORIES OF IMMUNITY. 



and tetanus may be explained in this way; the 

 evidence in favor of a chemical union between 

 the toxine and antitoxine already exists, and in 

 the same way there may be supposed to exist a 

 similar affinity between the toxine and the cells 

 of the tissues upon which it exerts its action. If 

 these affinities be satisfied — if the toxine is 

 bound to the tissue cell by the haptophorous 

 atom-group — the condition called susceptibility 

 appears, and the specific results of the toxic 

 action make their appearance; this of course 

 being the interference with -the normal metabol- 

 ism of the cell by having the cell molecule dis- 

 turbed and perhaps destroyed. 



So, also, an explanation of the production of 

 the anti-toxine may be built up on this supposi- 

 tion. "It is impossible to conceive that the 

 affinities in the brain cell to which, for example, 

 the tetanus toxine becomes attached, are ordi- 

 narily of no use in the cellular metabolism. They 

 must bear a part in the latter, or else they would 

 be examples of absolutely useless mechanism in 

 the body. Now the process of immunization 

 consists in its initial stages in the administration 



48 



