PREFACE 



servation, when yet incomplete, may give 

 rise to as many theories as ever pure spec- 

 ulation did. The whole subject indeed is 

 relatively so new that only those who have 

 been investigating it know how vast its 

 field is, and how much of that field is still 

 unexplored. It is unpleasant for a sci- 

 ence to admit that about its main points 

 it has little but hypotheses to offer, but 

 for the present that is the most biol- 

 ogy can do. Nor is this at all to its dis- 

 credit, for the growth of any science re- 

 quires time, and none more so than this 

 particular and great science. 



This book, however, is written to show 

 that enough has been demonstrated al- 

 ready to prove that the hypothesis of 

 earthly life ever having had a spontaneous, 

 or mechanical, or physico-chemical origin, 

 is wholly untenable. This conclusion, 

 though supported also by other strong 

 evidence, is the only deduction permissible 



