July 23, 1903] 



NATURE 



283 



On replacing the iodine atom in this molecule by an opti- 

 cally active group of atoms, viz. by the dextrobromocamphor- 

 sulphonic residue, two salts are obtained, each of which 

 contains an optically active basic part and an optically 

 active acidic part ; these are salts of the kinds d-B, d-A 

 and i-B, d-A, and can be separated by crystallisation from 

 a convenient solvent, and, after separation has been effected, 

 each salt may be reconverted into the iodide. These re- 

 generated iodides are found to be optically active in solu- 

 tion, and the conclusion is consequently drawn that optical 

 activity is an attribute of the asymmetric pentavalent 

 nitrogen atom as well as of the asymmetric tetravalent 

 carbon atom. The optical activity of this substituted 

 ammonium compound indicates that its molecule has an 

 enantiomorphous configuration, and is extended in three- 

 dimensional space ; the exact nature of this configuration 

 is not yet known, inasmuch as a space arrangement of five 

 groups is concerned, but the environment of the nitrogen 

 atom in ammonium salts is clearly not a simple tetrahedral 

 one. Just as enantiomorphism has been proved to be an 

 attribute of the asymmetric nitrogen atom, we have also 

 demonstrated that asymmetric tetravalent atoms of sulphur, 

 selenium and tin give rise to optical activity ; optically 

 active substances having the constitutions shown below 

 have been prepared, and we are thus well on the way to- 

 wards obtaining a complete stereochemical scheme em- 

 bracing all the elements : — 



CH, 



CoHg 



CfiHg 



CH, 



CH3 C2H6 



Se 



Sn 



CI CH,.COOH CI CH5.COOH 



C3H7 



It has been mentioned that optically active substances 

 occur as such, rather than in the compensated form, in 

 many animal and vegetable products, and also that when 

 a substance containing an asymmetric carbon atom is pre- 

 pared synthetically in the laboratory, it is of necessity 

 obtained in the compensated form, or as a mixture in equal 

 proportion of the dextro- and the laevo-isomerides. Taken 

 together, these two facts have a very interesting bearing 

 upon our speculations as to the origin of animal and vege- 

 table life. Optically active substances have been isolated 

 as products of the vital activity of all forms of animal or 

 vegetable life which have been properly examined, but in 

 spite of this they are never obtained directly as laboratory 

 products ; some enantiomorphous influence has always to 

 be employed in their synthetic preparation, just as Pasteur 

 applied enantiomorphism, either of method or of material, 

 to the resolution of compensated substances. It was very 

 strenuously argued by Prof. Japp, in his presidential 

 address to the Chemical Section of the British .\ssociation 

 in 1898, that no matter how successful we may be in re- 

 ducing the problems relating to vital processes to mere 

 questions of physics and chemistry, a residuum will always 

 evade explanation by such means ; this residuum will involve 

 the discussion of the way in which the first enantiomorphous 

 substance was resolved into its optically active components. 

 This question involves the introduction of an enantio- 

 morphous agency at some period during the evolutionary 

 development of living matter. In attributing difficulty to 

 the solution of this residuary problem, Dr. Japp implies 

 that the enantiomorphous agency, the cooperation of which 

 is essential, must be an intelligent agency. Let us ask 

 ourselves whether the enantiomorphous agency premised is 

 necessarilv other than one acting fortuitously. The 

 assumption of a fortuitously enantiomorphous agency is 

 certainlv all that need be made to explain the building up 

 of many enantiomorphous systems. The dead universe 

 itself, as we know it, is enantiomorphous, but this fact has 

 never been regarded as a valid argument against the 

 current hypothesis as to the cosmic origin of our planet. 

 Some degree of obscurity is, however, introduced into the 

 discussion of the primitive origin of the optically active 

 substances now produced by animals and plants by the 

 probability that ages of evolution have transformed the 

 primeval optically active substance into multitudes of other 

 and more complex products — have, in fact, accentuated the 

 enantiomorphism to such an extent that physiological 

 chemistry is now almost entirely the chemistry of enantio- 



NO. 1760, VOL. 68] 



morphous substances. If in any particular case, however, 

 we can show that an optically active substance can be 

 locally accumulated by the aid of some enantiomorphous 

 agency acting purely fortuitously, it will be clear that the 

 formation of the first optically active substance was not 

 necessarily the work of an intelligent enantiomorphous 

 agency. Such a species of separation of an optically active 

 substance from a compensated one can be readily brought 

 about in the laboratory. Pasteur showed that on crystal- 

 lising the sodium ammonium salt of compensated tartaric 

 acid (racemic acid) at ordinary temperature, large crystals 

 separate, each of which consists of the salt of one or other 

 of the d- and i-tartaric acids, the separation being brought 

 about by the first of the Pasteur methods. If one of these 

 crystals be selected casually, without the exercise of any 

 selective intelligence, and used as a nucleus for inducing 

 the crystallisation of further large quantities of the original 

 solution, it will cause the separation of salt of its own kind, 

 and ultimately a large quantity of salt of one of the optically 

 active tartaric acids can be accumulated as a result of the 

 introduction of an enantiomorphous agency such as might 

 act fortuitously in a non-living universe. The probability 

 of such a fortuitous agency arising would naturally be far 

 greater in a living universe. 



Again, suppose that at its origin life were carried on 

 non-enantiomorphously, and that it involved the consump- 

 tion and the production only of non-enantiomorphous sub- 

 stances and of compensated mixtures ; it may well be fore- 

 seen that a stage in development might arise when each 

 individual, in view of the increasing complexity of his 

 vital processes, would have to decide to use only the one 

 enantiomorphous component of his compensated food, and 

 so evade an otherwise necessary duplication of his digestive 

 apparatus. Acting unintelligently or fortuitously, one-half 

 of the individuals would become dextro-beings, whilst the 

 other half would become laevo-individuals ; the succeeding 

 generations would thus be of two enantiomorphously re- 

 lated configurations. It is, however, very difficult to believe 

 that the natural selective operations which have been instru- 

 mental in conducting living organisms to their present 

 stage of development would allow the perpetuation of this 

 state of affairs for any considerable period ; some fortuitous 

 enantiomorphous occurrence would temporarily give the 

 one configuration the advantage over the other, an advan- 

 tage which would be quickly accentuated and would involve 

 the permanent disappearance of the weaker configuration. 



The kind of difficulties involved in the existence, side by 

 side, of dextro- and L-evo-individuals such as these may 

 be shown by a simple illustration. There is no reason con- 

 nected with human enantiomorphism why vehicular traffic 

 should be forced to keep to one side of the road rather than 

 to the other ; as, however, the conditions of civilised life 

 have gradually become more complex, economic reasons 

 have arisen causing us to make an enantiomorphous selec- 

 tion, and in this country we arbitrarily force the traffic to 

 keep to the left ; other countries also make an arbitrary 

 and sometimes a different selection. Even if, when legisla- 

 tion on this matter first became necessary, the population 

 had been equally and obstinately divided upon the question 

 of the rule of the road, we cannot doubt that by this time 

 the question would have been satisfactorily and finally 

 settled by the extermination of one or other of the enantio- 

 morphously inclined parties without the cooperation of any 

 intelligent enantiomorphous agency. 



I mentioned that Pasteur gave a third method for the 

 resolution of compensated substances, a method depending 

 upon the selection exercised by living organisms upon the 

 enantiomorphously related components of the mixture. He 

 found, for instance, on allowing the mould Penicillium 

 glaucum to grow in a solution containing compensated 

 tartaric acid, that the mould used the d-tartaric acid as a 

 food-stuff, and rejected the laevo-isomeride, which latter 

 could ultimately be separated from the solution. The kind 

 of method thus indicated has been applied with success in 

 a great number of cases, and is, in the end, merely a special 

 application of Pasteur's second method. During recent 

 years a considerable change has taken place in our views 

 upon the action of the lower organisms upon their food- 

 stuffs. It was formerly supposed, for example, that the 

 fermentation of sugar by an ordinary beer yeast is a part 



