20 IMMUNE SERA 



plasia is not, therefore, the direct result of external 

 irritation, and cannot be, since the action of the 

 irritant is destructive and is confined to the cells 

 or integers of cells that it destroys, but occurs 

 rather indirectly as a function of the surrounding 

 uninjured tissues that have been excited to bio- 

 plastic activity through the removal of the restraint 

 hitherto exerted by the cells destroyed by the 

 irritant; and, finally, when such bioplastic activity 

 is called into play there is always hypercompen- 

 sation i.e. there is more plastic material gene- 

 rated than is necessary to compensate for the 

 loss. 



Ehrlich points out that owing to the combination 

 of the toxin with the side chain of a cell, these 

 side chains are practically lost to the cell ; that the 

 latter or its fellows now produces new side chains to 

 replace this loss, but that this production always 

 goes so far as to make a surplus of side chains ; that 

 these side chains are thrown off by the cell as 

 unnecessary ballast, and then circulate in the blood 

 as antitoxin. The same substances, therefore, which 

 when part of the cell combine with the haptophore 

 group of the toxin, enabling that to act on the cell, 

 when circulating free in the blood combine with 

 and satisfy this haptophore group of the toxin, 

 and prevent the poison from combining with and 

 damaging the cells of the organism. 



It does not follow from Ehrlich's theory that the 



