THEORIES OF IMMUNITY. 



how it gets there; if it does not so exist, then 

 the bacterium must be conceded to enter the 

 tissue cell at the first in order to start the exci- 

 tation resulting in the production of the immune 

 bodies; if this be the explanation, then Metch- 

 nikoff's contention that phagocytosis — at least 

 cellular action — takes place in the very first 

 instance must be adopted. 



In the second place the query arises as to 

 why, if the bacteria must meet both complement 

 and immune body in the cell, why is the latter 

 produced so much in excess and not the former? 

 On the basis of the supposition that the comple- 

 ment exists normally, and that the immune 

 body is the result of an excess of cell activity 

 set in motion by the taking up of the hapto- 

 phorous atom-groups needed in the ordinary 

 metabolism by the bacterial atom-groups of the 

 same nature, this is easily understood, because 

 this new vital activity goes on in excess and may 

 be supposed to result in the production of a 

 great excess of the atom-groups representing the 

 immune body. 



It is most probably the case that the reactions 



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