THE ORIGIN OF LIFE: A CHEMIST'S FANTASY 317 



formation, one form rather than the other might have been pro- 

 duced. An active substance thus generated and selected out 

 might then become the origin of a series of asymmetric syntheses. 

 How the complicated series of changes which constitute life may 

 have arisen we cannot even guess at present ; but when we 

 contemplate the inherent simplicity of chemical change and bear 

 in mind that life seems but to depend on the simultaneous 

 occurrence of a series of changes of a somewhat diverse order, it 

 does not appear to be beyond the bounds of possibility to arrive 

 at a broad understanding of the method of life. Nor are we likely 

 to be misled into thinking that we can so arrange the conditions 

 as to control and reproduce it ; the series of lucky accidents 

 which seem to be required for arrangements of such complexity to 

 be entered upon is so infinitely great." 



It is permissible now, perhaps, to enter somewhat more at 

 length into an explanation of the changes contemplated in this 

 passage. 



Growth most certainly proceeds on determined lines — 

 " directive influences are the paramount influences at work in 

 building up living tissues " (Winnipeg address). What Prof. 

 Schafer has not pointed out, in contrasting the growth of 

 inorganic and of animal matter, is that Nature now works on 

 very narrow lines, making use of but little of the wealth of 

 material primarily at her disposal. Selective influences must 

 have been at work from the earliest stages of the evolution of 

 life onwards. It is in this respect perhaps more than any other 

 that the inorganic differs so greatly from the organic ; it is this 

 circumstance too more than any other which makes it so 

 improbable that life should arise frequently de novo from simple 

 materials not themselves the products of vital action. 



To give an example, the hexose, glucose — a constituent of 

 every plant and animal — is one of sixteen isomeric compounds, 

 all represented by the formula 



CH a (OH) . CH(OH) . CH(OH) . CH(OH) . CH(OH) . COH. 



Of these sixteen compounds, fourteen have actually been pre- 

 pared in the laboratory and they differ considerably in 

 properties. The differences are due to the different distribution 

 in space of the H and OH groups relatively to the carbon 

 atoms. The sixteen compounds form eight pairs and as the 

 individual members of each pair have the power of rotating 

 polarised light in opposite directions, though to an equal 



