PERSPECTIVES IN EVOLUTION — RITCHIE 257 



A second conclusion follows upon our analysis. Phenomena of 

 life elude treatment by the laws of thermodynamics, not necessarily 

 because living matter does not obey these laws, but because the 

 unknown conditioning of working organisms is too complex to 

 yield to analysis applicable to inorganic states. Nor does it seem 

 likely, since livingness exists within a very limited range of tem- 

 perature and is readily extinguished by interferences, that it can ever 

 be subjected to the sort of analysis which has led to the interpreta- 

 tion of the constitution of physical matter. It seems logical there- 

 fore to take as axiomatic the existence of life, not as a vital force 

 which animates something different, namely matter, but as the ac- 

 tivity of an atomic combination, the very activity of which renders 

 it unanalyzable bj^ the standard methods of the physicist and chem- 

 ist. Thus, as one of the greatest of living physicists, Niels Bohr, 

 has pointed out, the biologist would accept for the living world a 

 position analogous to that accepted by the physicist for the non- 

 living. "The existence of life must be considered as an elementary 

 fact that cannot be explained, but must be taken as a starting point 

 in biology, as in a similar way the quantum of action, which appears 

 as an irrational element from the point of view of mechanical 

 physics, taken together with the existence of the elementary particles, 

 forms the foundation of atomic physics" (Bohr, 1933, p. 457). 



And the biologist, admitting "life," may build up a whole body 

 of biological theory, as distinctive and peculiarly his own, and as 

 logical in the logic of probability which Professor Darwin advocates, 

 as are the theories of the physicist or the chemist in their own 

 limited fields. 



LENGTHENING OF LIFE PERSPECTIVE 



There is another notable development of this century which must 

 affect evolutionary thought, the expanding idea of the time during 

 which the earth and life upon the earth have been in existence. 

 Broadly three methods of making the estimation have been can- 

 vassed — physical, geological, and biological; but from the funda- 

 mental uncertainty which attaches to conditions of life, it may be 

 assumed that biological methods are bound to be problematical and 

 unsatisfactory. To illustrate the enormous change in outlook which 

 has taken place let me mention a few of the estimates. 



An early estimate was biological, founded upon the genealogies 

 of the Book of Genesis. It used to be familiar in the reference 

 column of the Bibles of a past generation such as Bagster's Polyglot 

 Bible, where the creation is set down precisely at 4004 B. C. In the 

 eighteenth century, Buffon, a far-seeing naturalist who had views 

 upon evolution ahead of his time, put the matter to the test of 

 experiment. Recognizing in the earth a cooling body, he measured 



