418 ON CONCRETIONS, SPICULES, ETC. [ch. 



crux of the difficulty ; for they at once bid us enquire whether in 

 nature, external to and antecedent to life, there be not some 

 asymmetry to which we may refer the further propagation or 

 "begetting" of the new asymmetries: or whether in default 

 thereof, we be rigorously confined to the conclusion, from which 

 Japp "saw no escape," that "at the moment when life first arose, 

 a directive force came into play, — a force of precisely the same 

 character as that which enables the intelligent operator, by the 

 exercise of his will, to select one crystallised enantiomorph and 

 reject its asymmetric opposite*." 



Observe that it is only the first beginnings of chemical 

 asymmetry that we need to discover ; for when asymmetry is once 

 manifested, it is not disputed that it will continue "to beget 

 asymmetry." A plausible suggestion is now at hand, which if it 

 be confirmed and extended will supply or at least sufficiently 

 illustrate the kind of explanation which is required f. 



We know in the first place that in cases where ordinary non- 

 polarised light acts upon a chemical substance, the amount of 

 chemical action is proportionate to the amount of light absorbed. 

 We know in the second place J, in certain cases, that light circularly 

 polarised is absorbed in different amounts by the right-handed or 

 left-handed varieties, as the case may be, of an asymmetric 

 substance. And thirdly, we know that a portion of the hght 

 which comes to us from the sun is already plane-polarised hght, 

 which becomes in part circularly polarised, by reflection (according 

 to Jamin) at the surface of the sea, and then rotated in a 

 particular direction under the influence of terrestrial magnetism. 

 We only require to be assured that the relation between ab- 

 sorption of light and chemical activity will continue to hold 

 good in the case of circularly polarised light; that is to say 



* In accordance with Emil Fischer's conception of "asymmetric synthesis," 

 it is now held to be more likely that the process is synthetic than analytic : more 

 likely, that is to sa}% that the plant builds up from the first one asymmetric body 

 to the exclusion of the other, than that it "selects" or "picks out" (as Japp sup- 

 posed) the right-handed or the left-handed molecules from an original, optically 

 inactive, mixture of the two; cf. A. McKenzie, Studies in Asymmetric Synthesis, 

 Journ. Chem. Soc. (Trans.), Lxxxv, p. 1249, 1904. 



f See for a fuller discussion, Hans Przibram, Vitalitdt, 1913, Kap. iv, Stoff- 

 wechsel (Assimilation und Katalyse). 



X Cf. Cotton, ^Jiw. de Chim. et de Phijs. (7), viii, pp. 347-432 (cf. p. 373), 1896. 



