10 



SCIENCE. 



[N. S. Vol.. XX. No. 496. 



papers on the behavior of certain enzymes 

 in the fermentation of sugars, in which he 

 pointed out that in order to work as fer- 

 ments the enzymes must possess a certain 

 stereo-chemical structure, bearing a definite 

 relation to the stereo-chemical structure of 

 the sugar. Without this relation fermenta- 

 tion can not take place. In order to 

 make his meaning plain Fischer employed 

 a figure which has since become famous. 

 He said, in speaking of certain glucosides: 

 'Enzyme and glucoside must fit into each 

 other as a key into a lock in order that the 

 one may be able to exert a chemical action 

 on the other.' In one of these papers 

 Fischer suggests that the idea of related 

 molecular configuration of enzyme and fer- 

 mentable body may prove of value in 

 physiological investigation as well as in 

 chemistry. We have apparently in this 

 prediction of Fischer made ten years ago 

 the basis of the Ehrlich hypothesis. 



Without going into minute details, the 

 Ehrlich notion of bacterial or toxin action 

 on the cells of the body, and immunity 

 from the same, is briefly this. Bacteria, 

 animal cells and toxins are all complex 

 aggregations of more or less complex 

 molecules. The latter have certain con- 

 figurations dependent on the presence of 

 side chains or side groups, to borrow an 

 expression from organic chemistry. These 

 side chains are dijectly or indirectly the 

 points of attack or defense in the action 

 of the several bodies on each other. In 

 order that a substance may behave as a 

 poison or toxin to cells of the body, both 

 cells and toxins must, therefore, possess 

 certain reciprocal configurations. It has 

 been suggested by Ehrlich that it is through 

 the presence, of these side gi'oups that the 

 cells absorb their necessary nutriment and 

 elaborate new structures from it. Some of 

 the side chains may be constructed to com- 

 bine with fats, some with carbohydrates 

 and some with proteins, but in the presence 



of toxins or bacteria with the right kind 

 of side chains combination with' these may 

 take place instead. Certain phenomena 

 seem to indicate that this combination is 

 not a direct one, at any rate not always 

 direct, and the conception of an inter- 

 mediary body or linking complex has been 

 developed. This intermediary body must 

 itself possess two groups with special con- 

 figurations; one of them fits it to combine 

 with the cell, while the other brings about 

 the combination with the toxic molecule. 



The complicated nomenclature called into 

 existence to describe and express satisfac- 

 torily the conceptions of this interesting 

 theory appears at first sight a great draw- 

 back in the way of readily following it. 

 There are cytophil groups and toxophil 

 groups, and both of these may be called 

 haptophorous groups because they carry 

 the combining or uniting property. Other 

 terms employed sound equally strange to 

 the chemist, but a little patient study dis- 

 closes what is meant and we are obliged to 

 recognize in the new doctrine an important 

 widening out of biochemical science. Of 

 course no one assumes that the theory, or 

 the various other theories which have 

 grown up around it, will persist in the 

 present form. The chemistry of living 

 things is admittedly the most complex of 

 all kinds of chemistry, For new ideas we 

 must have new figures and these of Ehrlich 

 in the side chain theory are not more un- 

 real than were the figures employed in the 

 early days when a general chemistry began 

 to be evolved from the atomic theory of 

 Dalton. Besides this, the stereo-chemical 

 speculations of Ehrlich and his school pre- 

 sent for the first time a tangible working 

 hypothesis to account for the phenomena 

 of toxicity and immunity. In many re- 

 spects the hypothesis or theory will suffer 

 modification and so discard what is useless 

 or false. But already it has stimulated 

 investigation enormously and created in 



