824; REPORT— 1898. 



dissociated, however, from the previous production of the racemoid form, 

 may be illustrated by the fermentation of dextro-tartaric acid in the action, 

 studied by Pasteur and already referred to, of a mould on racemic acid, the Isevo- 

 taitaric acid remaining- untouched, and by numerous similar fermentations since 

 discovered. Selective consumption is not restricted to living ferments; various 

 cases are known of enzymes, or soluble ferments, which can effect the hvdrolysis 

 of one glucoside, but not of its enantiomorph. As Emil Fischer, who studied this 

 phenomenon, says : ' Enzyme and glucoside must fit each other like key and lock, 

 in order that the one may exercise a chemical action on the other.' And a similar 

 selective action, embracing the much more complex phenomenon of alcoholic fer- 

 mentation, is displayed by E. Buchner's soluble zymase obtained from yeast cells. 



It is true, moreover, that the organism sometimes produces both enantiomorphs. 

 Thus the lactic ferment converts carbohydrates into racemoid lactic acid ; ordinary, 

 or Ifflvo-rotatory, asparagine is accompanied in plants, as Piutti showed, by a small 

 quantity of its optical isomeride ; and there are other cases. 



These facts might be taken as evidence in favour of Fischer's view that selec- 

 tive consumption is the cause of the phenomenon we are discussing. But I do not 

 think that, la the present state of our knowledge, we can decide between the two 

 views. For that matter both may be correct, each may explain particular cases. 

 What 1 wish to point out is that Fischer's statement that the ' miraculous ' 

 character of the phenomenon is eliminated by his assumption appears open to 

 question. It is ju.st as much, or as little, miraculous after as before. The pro- 

 duction of a single asymmetric form, and the destruction of one of two opposite 

 asymmetric forms, are problems of precisely the same order of difficulty, and there 

 are only two ways in which either of theru has ever been solved : firstly, by the 

 direct action of living matter, and, secondly, by the use of previously existing 

 asymmetric non-racemoid compounds, which are, in the last resort, due to'the action 

 of life. Directly or indirectly, then, life intervenes. 



Doubtless this will appear a very extraordinary statement in view of Jung- 

 fleisch's synthesis of racemic acid and its resolution into dextro- and Itevo-tartaric 

 acids by the crystallisation of the sodium ammonium salts. The process does not 

 take place in a living organism ; nor is the aid of life invoked in the shape of a 

 micro-organism as in Pasteur's third method of separation. No asymmetric base 

 of vegetable origin is employed as in Pasteur's second method, so that the indirect 

 action of life through its products is also excluded ; sodium and ammonium are 

 .symmetric inorganic radicles, and no substance of one-sided asymmetry is intro- 

 duced from beginning to end. The process is one of ordinary crystallisation ; the 

 two forms are deposited side by side, the operator afterwards picking out the right 

 and left crystals and separating them. The reason why the two tartrates crystal- 

 lise out and not the racemate, is that at the ordinary temperature of the air at 

 which the crystallisation is conducted they are less soluble than the racemate. 

 At a higher temperature, on the other hand, these solubilities are reversed and the 

 racemate is deposited. The conditions are precisely those which govern the forma- 

 tion or non-formation of ordinary double salts. 



Consequently, the overwhelming majority of chemists hold that the foregoing 

 synthesis and separation of optically active compounds have been eflfected without 

 the intervention of life, either directly or indirectly. Every manual of stereo- 

 chemistry emphasises this point. 



I have already hinted that I hold a contrary opinion. I have held it for 

 some time, but have not ventured to give public expression to it, except in 

 lecturing to my students. I was deterred chiefly by the impression that I stood 

 alone hi my belief. I find, however, that this was a mistaken impression. In a 

 lecture on ' Pasteur as the Founder of Stereochemistry,' which Professor Crum 

 Brown dehvered before the Franco^Scottish Society in July 1897, and which is 

 published in the ' Revue fran^aise d'Edimbourg,' he says, referring to the separation 

 of enantiomorphs by crystallisation : — 



' The question has often occurred to me : Do we here get rid of the action of a 

 living organism ? Is not the observation and deliberate choice by which a human 

 being picks out the two kinds of crystals and places each in a vessel by itself the 



