6 A : / :I::V.": * ' >BEFACE 



termed protoplasm, but of nuclear matter or chromatin : a suggestion 

 which appears by no means improbable. 



If the honoured names of Charles Darwin, Ernst Hackel, and August 

 Weismann are not found in the following pages, it is because exigencies 

 of space and time rendered it necessary to deal mainly with the more 

 modern developments of this chapter of evolutionary history. For other 

 but not less cogent reasons all metaphysical speculations on the subjects 

 dealt with have been avoided. The study of Natural Knowledge, as the 

 Eoyal Society still quaintly describes in its title the investigation of the 

 phenomena of Nature, is never properly advanced if mixed up with the 

 ' supernatural ' or if metaphysics is appealed to for the explanation of 

 scientific problems which cannot at once be solved by ordinary scientific 

 methods ; and it behoves us to eliminate all considerations involving the 

 intervention of supernatural agencies just as much in connection with 

 scientific inquiries into the nature and origin of life as with all other 

 matters which are properly the subject of scientific investigation. This is 

 not materialism, but common sense. 



The first part of the subject of this Address is dealt with at consider- 

 able length and in a strictly scientific spirit by Le Dantec in ' The Nature 

 and Origin of Life'; as well as by Dastre in the book mentioned on 

 the next page. To works such as these the reader is referred for the 

 numerous details which it is impossible to include within the limits of 

 a short Essay. 



UNIVERSITY, EDINBURGH, 

 October, 1912. 



