viii Preface. 



antagonism to so large a proportion of the scien- 

 tific world and, too, upon subjects of strictly 

 scientific import. That he does thus find himself 

 placed in such relations at the present time, has not 

 been a matter of his own seeking. No other con- 

 sideration than the profoundest sense of duty and 

 responsibility could have influenced him in the 

 course pursued. Perhaps some apology is yet 

 due for so boldly trespassing upon hypotheses 

 which were very generally thought to be well 

 established, and certainly secure from such treat- 

 ment. 



The attempt, in a measure, to develop so ex- 

 tended a field of research, in so few pages, has led 

 to much crudeness in the presentation. For this 

 a reasonable indulgence may be claimed. 



