250 THE FITNESS OF THE ENVIRONMENT 



in adopting this somewhat rigid logical 

 method, tedious and perhaps unnecessary 

 repetition is involved, but the advantages of 

 care at this stage of the inquiry seem to be 

 very great, for it is not easy to survey so 

 large a field, and at best certainty that impor- 

 tant oversights have been avoided is obviously 

 impossible. For example, peculiarities like the 

 anomalous expansion of water, or the relation 

 of carbonic acid and water to the carbohy- 

 drates are not to be foreseen. On the other 

 hand, the more general characteristics of 

 matter are well known and, for the most part, 

 must reveal themselves to diligent search. 



ANALYSIS OF THE EVIDENCE 



First the natural phenomena which seem to 

 be concerned in fitness may be brought to- 

 gether analytically, and their effect briefly 

 summarized. 



NATURAL PHENOMENA WHICH PROMOTE FITNESS 

 IN THE ENVIRONMENT 



I. The occurrence of great quantities of 

 water and carbon dioxide outside 

 the solid crust of an astronomical 

 body. 



