4 8o SCIENCE PROGRESS 



The question appears to have been settled in a somewhat 

 unexpected manner. Cotton, 1 examining the absorption of 

 dextro circularly polarised light by copper ammonium tar- 

 trate, found that the two tartrates did not possess identical 

 powers of absorption. Now, if light is absorbed by any 

 molecule, some extremely delicate rearrangement of the 

 molecule's internal structure must take place ; for we cannot 

 imagine that a vibration can be stopped without some energy 

 being expended in stopping it or changing its amplitude. 

 Therefore, in the case of the dextro and laevo forms of copper 

 ammonium tartrate, more energy is being used up by the one 

 form than by the other ; and hence the intramolecular readjust- 

 ment is greater in the one isomer than in the other. In other 

 words, dextro circularly polarised light is an agent which 

 favours one form of tartaric acid rather than the other. Now, 

 Byk 2 has pointed out that light is circularly polarised by the 

 surface of the sea, and that one variety of the circularly polarised 

 light predominates on the earth's surface. This obviously fur- 

 nishes us with an asymmetric agent whose application, as far as 

 the earth is concerned, is nearly universal ; and it seems not 

 improbable that some such cause, acting under favourable 

 conditions, may have given rise to a preponderance of a right- 

 handed or left-handed form at one particular period in geological 

 history. Until some active substance is actually synthesised 

 by this method, however, the question must be regarded as, 

 at least technically, an open one. 



It should be noted that once the presence of an asymmetric 

 substance is granted, the subsequent steps up to the present 

 complex series of naturally occurring asymmetric forms become 

 simple to understand. A very small quantity of an asymmetric 

 acid, under suitable conditions, may serve to resolve any 

 quantity of a racemic base without losing any of its peculiar 

 asymmetry ; while each portion of base resolved into its 

 antipodes becomes a new centre for the resolution of racemic 

 acids, which in their turn may serve to resolve new bases, and 

 so on ad infinitum. The case is analogous to that of ordinary 

 animal reproduction, since with each generation the reproductive 

 power increases in geometrical proportion. 



In conclusion, it may be pointed out that the accumulation 



1 Cotton, Ann. chim. phys. [7], 8, 373 (1896). 



2 Byk, Zeit. physikal. Chetn. 49, 641 (1904) ; Ber. 37, 4696 (1904). 



