256 ON VARIABILITY AND ADAPTATION 



There are, however, serious objections to this view. As 

 pointed out by Abderhalden, the anaphylactic phenomena are 

 specific ; it is only the protein first introduced that sets up 

 disturbance ; on subsequent injection other proteins are not 

 affected, whereas Abderhalden's proteolytic and peptolytic 

 enzymes are active in respect to any protein. The only safe 

 conclusion is, therefore, that in these data we have evidence of 

 the development of two stages : 



1. Elaboration and discharge into the blood plasma, within 

 forty-eight hours, of indifferent proteoclastic and peptolytic 

 enzymes, affording Abderhalden's phenomenon. 



2. The gradual production of more highly developed specific 

 proteoclastic enzymes, having the power of rapid dissociation 

 of the particular protein introduced, with liberation in the course 

 of a few minutes of sufficient toxic disintegration product or 

 products to set up symptoms. 



I should note in passing that it cannot be regarded as ab- 

 solutely settled as yet whether it is the enzymes liberated into 

 the blood plasma that are the essential cause of the anaphylactic 

 symptoms, or whether the phenomena are due to intracellular 

 dissociation in specific groups of cells, such as certain cell groups 

 and centres in the nervous system. If these cells under the 

 action of the first dose have been stimulated to produce and 

 consequently store the non-specific enzyme, the moment the 

 foreign protein comes into contact with their cytoplasm, or is 

 absorbed by them, it will undergo degradation. An extra- 

 ordinarily minute dose of foreign protein in this way, by acting 

 on or being acted on by specific cells, might set up fatal results. 

 The rapidity with which anaphylactic phenomena may show 

 themselves, and that upon the introduction of extraordinarily 

 small amounts of any particular protein, rather favours the latter 

 view : it suggests that there is a selective taking up of the protein 

 by particular cells, cells whose due and ordered action is essential 

 for continued existence. 



Immunity 



What I want to bring specially before you is that the two 

 stages above postulated lead up to a third ; in other words, that 

 anaphylactic phenomena afford us explanation of the nature 

 of immunity. By cautious reinjection of the foreign disharmoni- 



