XLIL THE MULTIPLICITY OF ANTIBODIES OCCURRING 

 IN NORMAL SERUM. 1 



By Dr. MAX NEISSER, Member of the Institute. 



FOLLOWING the fundamental researches made by Fliigge and 

 Buchner and their pupils on the bactericidal power of normal 

 blood, we have come to ' recognize a large number of properties 

 possessed by normal serum. According to our present knowledge 

 we must regard these properties as due to the presence of anti- 

 bodies in the broadest sense. 



Thus far the only theory which has satisfactorily accounted 

 for the origin of these antibodies, from a physiological standpoint 

 and without invoking the aid of teleological "protective substances," 

 is Ehrlich's Side-chain Theory. According to this the cells of the 

 organism produce substances, side-chains, whose physiological 

 function, so long as they are part of the cell, is to lay hold of 

 certain foodstuffs. Side-chains thus anchored are replaced by the 

 cell, and when this regeneration is excessive, the surplus side 

 chains are thrust off into the blood. As a result of this, the blood 

 serum contains a large number of different side-chains. For 

 example, one variety of these side-chains may happen to have an 

 affinity for a particular toxin; it will be found possible, by care- 

 fully injecting this toxin, to increase the regeneration and thrusting- 

 off to an extraordinary degree, and thus an immunity is produced 

 against that toxin. From this standpoint, then, immunity is 

 regarded as merely a quantitative increase in the exercise of a 

 normal function. 



This view has important bearings on our conception of the 

 antibodies occurring in normal serum. It is apparent that the 

 diversity of the antibodies which can be produced artificially, is 

 entirely analogous to the variety of antibodies present normally. 



1 Reprinted from Deutsche med. Wochenschr., No. 49, 1900. 



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