652 ON CONCRETIONS, SPICULES, ETC. [ch. 



that the asymmetrically polarised light will tend to more rapid 

 decomposition of those^ molecules by which it is chiefly absorbed. 

 This latter proof is said to be furnished by Byk*. who asserts 

 that certain tartrates become unsymmetrical under the continued 

 influence of the asymmetric rays. Here then we seem to have 

 an example, of a particular kind and in a particular instance, an 

 example hmited but yet crucial if confirmed, of an asymmetric 

 force, non-vital in its origin, which might conceivably be the 

 starting-point of that asymmetry which is characteristic of so many 

 organic products. 



The mysteries of organic chemistry are great, and the differences 

 between its processes or reactions as they are carried out in the 

 organism and in the laboratory are manyt; the actions, catalytic 

 and other, which go on in the living cell are of extraordinary 

 complexity. But the contention that they are different in kind 

 from ordinary chemical operations, or that in the production of 

 single asymmetric compounds there is actually, as Pasteur main- 

 tained, a "prerogative of life," would seem to be no longer tenable. 

 Oiir historic interest in the whole question is increased by the 

 fact, or the great probability, that "the tenacity with which Pasteur 

 fought against the doctrine of spontaneous generation was not 

 unconnected with his belief that chemical compounds of x)ne-sided 

 symmetry could not arise save under the influence of hfej." But 

 the question whether spontaneous generation be a fact or not does 

 not depend upon theoretical considerations; our negative response 

 is based, and is soundly based, on repeated failures to demonstrate 

 its occurrence. Many a great law of physical science, not excepting 

 gravitation itself, has no higher claim on our acceptance. 



Let us return from this digression to the general subject of the 

 forms assumed by certain chemical bodies when deposited or 

 precipitated within the organism, and to the question of how far 

 these forms may be artificially imitated or theoretically explained. 



* A, Byk, Zur Frage der 8paltbarkeit von Racemverbindungen durch zirkular- 

 polarisiertes Licht, ein Beitrag zur primaren Entstehung optisch-activer Substanzen, 

 Zeitsch. f. physikal. Chetnie, xlix, pp. 641-687, 1904. It must be admitted that 

 positive evidence on these lines is still awanting. 



f Cf, (int. al.) Emil Fischer, Untersuchungen iiber Aminosduren, Proteine, etc. 

 Berlin, 1906. 



J Japp, loc. cit. p. 828. 



