RELIGION AND SCIENCE 253 



remains to be seen whether the same tendency is 

 perpetuated later. 



The evolutionary concept is to biology what the 

 doctrine of the conservation of energy has been in 

 the physico-chemical sciences — an indispensable pre- 

 liminary to proper methods of attack. But while 

 great stress has been laid on the various methods by 

 which evolution may be supposed to have taken place 

 — natural selection, Lamarckism, orthogenesis and 

 the rest — biology has concerned herself compara- 

 tively little with the form of the process in itself. 

 But it is here that evolution becomes of value to us 

 in our present search ; for once more we become 

 aware of a direction. Partly from the direct evidence 

 of palaeontology, partly from indirect evidence, but 

 along many converging lines, we can form an idea 

 of this direction which in broad outlines is unassailable. 



During life's existence on earth — a period to be 

 reckoned in hundreds and probably in thousands of 

 millions of years — there has been an increase in 

 various of its attributes. But just as in the inorganic 

 world electrons and atoms still exist as such side by 

 side with molecules, so also the earlier types of living 

 matter continue to exist side by side with the later. 

 The increase is not therefore seen uniformly in all 

 forms at once, but is most easily observed by studying 

 the maximum level attained. Size, for instance, is 

 one of these attributes ; and whereas to-day all 

 variations are to be found between ultra-microscopic 



