260 ON VARIABILITY AND ADAPTATION 



Thus, to conclude, I would lay down the following as summing 

 up the views here put forward as most satisfactorily harmonizing 

 the data at present in our possession. 



1. Whatever the nature of enzymes, the organism has the 

 power of elaborating new orders of these bodies in and from its 

 cells in response to the entrance into the tissues of foreign pro- 

 teins, and potential food-stuffs in general. 



2. The development of anti-bacterial immunity in an animal 

 is essentially the development of the power of parenteral digestion 

 by the tissues of the constituents (mainly protein) of the patho- 

 genic micro-organisms. 



3. This is rendered possible by the elaboration of a succession 

 of (mainly) proteoclastic enzymes. 



4. Three stages are to be recognized in this process : 



(a) The development of indifferent proteoclastic enzymes. 



(6) The development of specific proteoclastic enzymes, 

 splitting the bacterial proteins into highly poisonous and non- 

 poisonous moieties. 



(c) The development of toxoclastic enzymes which render 

 the disintegration products innocuous. 



5. Ectotoxins are to the micro-organism what discharged 

 enzymes are to the animal. They have all the properties of 

 enzymes. 



6. They are not themselves toxic, but proteoclastic, and it 

 is the products of their activity upon the proteins of the organism 

 that are the essential toxic substances. 



7. Antitoxic immunity is thus wholly distinct from anti- 

 bacterial immunity. It is a process not primarily of digestion 

 and disintegration, but, rather, of combination and fixation of 

 enzyme, so that this is no longer capable of attacking and dis- 

 integrating successive complex proteid molecules ; or, it may be, 

 one of development of toxoclastic enzymes by the tissues, which 

 disintegrate the toxic proteins as they are produced, rendering 

 them innocuous : or both. 



