TRANSACTIONS OF SECTION B. 825 



specific act of a living organism of a kind not altogether dissimilar to the selection 

 made by Penicillium glaucum ? But I do not insist on this, although I think it is 

 not unworthy of consideration.' 



It is this question, so precisely posed by Professor Crum Brown, that I would 

 discuss in detail. I think we shall find that the answer to it will be in the sense 

 which he indicates. The action of life, which has been excluded during the 

 previous stages of the process, is introduced the moment the operator begins to 

 pick out the two enantiomorphs. 



It will doubtless be objected that, if this is the case, there can be no such thing 

 as a synthesis of a naturally occurring organic compound without the intervention 

 of life, inasmuch as the synthetic process is always carried out by a living 

 operator. 



Here, however, we must draw an important distinction. In the great majority 

 of the operations which we carry out in our laboratories— such as solution, fusion, 

 vaporisation, oxidation, reduction and the like — we bring to bear upon matter 

 symmetric forces only — forces of the same order as those involved in the chance 

 motions of the molecules of a liquid or a gas. All such processes, therefore, might 

 conceivably take place under purely chance conditions, without the aid of an 

 operator at all. But there is another class of operations, to which Pasteur first 

 drew attention: those into which one-sided asymmetry enters, and which deal 

 either with the production of a single enantiomorph, or with the destruction (or 

 change) of one enantiomorph in a mixture of both, or with the separation of two 

 enantiomorplis from one another. We have already seen that such processes are 

 possible only under one-sided asymmetric influences, which may take the form 

 either of the presence of an already existing enantiomorph, or of the action of a 

 living organism, or of the free choice of an intelligent operator. They cannot 

 conceivably occur through the chance play of symmetric forces. 



We must, therefore, in classifying the actions of the intelligent operator, dis- 

 tinguish between those actions in which his services might conceivably be 

 dispensed with altogether and those in which his intelligence is the essential factor. 

 To the former class belongs the carrying out of symmetric chemical reactions ; to 

 the latter, the separation of enantiomorphs. 



Take the synthesis of formic acid — a symmetric compound — by the absorption 

 of carbon monoxide by heated caustic alkali. Given a forest fire and such natu- 

 rally occurring materials as limestone, sodium carbonate, and water, it would not be 

 difficult to imagine a set of conditions under which a chance synthesis of sodium 

 formate from inorganic materials might occur. I do not assert that the condi- 

 tions would be particularly probable ; still, they would not be inconceivable. But 

 the chance synthesis of the simplest optically active compound from inorganic 

 materials is absolutely inconceivable. So also is the separation of two crystallised 

 enantiomorphs under purely symmetric conditions. 



The picking out of the two enantiomorphs is, moreover, to be distinguished 

 from the process of similarly separating the crystals of two different non-enantio- 

 morphous substances, although this distinction is commonly ignored by classing 

 both processes together as mechanical, in opposition to chemical separations. In 

 the case of the non-enantiomorphs there may be differences of solubility, of specific 

 gravity and the like ; so that other means of separation, involving only the play of 

 symmetric forces, may be resorted to. Such a process may justly be regarded as 

 ' mechanical.' But the two crystallised enantiomorphs, as we have seen, have the 

 same solubility — at least in symmetric solvents ; the same specific gravity ; behave, 

 in fact, in an identical manner towards all symmetric forces ; so that no separa- 

 tion by such means is feasible. It requires the living operator, whose intellect 

 embraces the conception of opposite forms of asymmetry, to separate them. Such 

 a process cannot, by any stretch of language, be termed ' mechanical.' Conscious 

 selection here produces the same result as the unconscious selection exercised by 

 the micro-organism, the enzyme, or the previously existing asymmetric compound. 

 I need not point out that if the operator chooses to bring about the separation 

 by an asymmetric solvent, or some other asymmetric means, he is still making use 

 of his conception of asymmetry. He merely effects his end indirectly instead of 



