xviii PREFACE 



lem of energy and end with that of the evolution of form is 

 that these lectures were prepared and delivered midway in a 

 cosmic-evolution series which opened with Sir Ernest Ruther- 

 ford's^ discourse on "The Constitution of Matter and the 

 Evolution of the Elements," and continued with "The Evolu- 

 tion of the Stars and the Formation of the Earth," by Doctor 

 William Wallace Campbell,- and "The Evolution of the Earth," 

 by Professor Thomas Chrowder Chamberlin.^ My friend 

 George Ellery Hale placed upon me the responsibility of 

 weaving the partly known and still more largely unknown 

 narrative which connects the forms of energy and matter ob- 

 served in the sun and stars with the forms of energy and matter 

 which we observe in the bodies of our own mammalian ances- 

 tors. Certainly we appear to inherit some, if not all, of our 

 physicochemical characters from the sun; and to this degree 

 we may claim kinship with the stellar universe. Some of our 

 distinctive characters and functions are actually properties of 

 our ancestral star. Physically and chemically we are the off- 

 spring of our great luminary, which certainly contributes to 

 us all our chemical elements and all the physical properties 

 which bind them together. 



Some day a constellation of genius will unite in one labora- 

 tory on the life problem. This not being possible at present, 

 I have endeavored during the past two years^ for the purposes 



1 Rutherford, Sir Ernest, "The Constitution of Matter and the Evokition of the 

 Elements," first series of lectures on the William Ellery Hale foundation, delivered in 

 April, 1914; Pop. Sci. Mon., August, 1915, pp. 105-142. 



2 Campbell, William Wallace, "The Evolution of the Stars and the Formation of the 

 Earth," second series of lectures on the WilUam Ellery Hale foundation, delivered De- 

 cember 7 and 8, 1914; Pop. Sci. Man., September, 1915, pp. 209-235; Scientific Monthly, 

 October, 1915, pp. 1-17; November, 1915, pp. 177-194; December, 1915, pp. 238-255. 



' Chamberlin, Thomas Chrowder, "The Evolution of the Earth," third series of lec- 

 tures on the William Ellery Hale foundation, delivered April 19-21, 1915; Scientific 

 Monthly, May, 1916, pp. 417-437; June, 1916, pp. 536-556. 



'' I first opened a note-book on this subject in the month of April, 19 15, when I was 

 invited by Doctor George Ellery Hale to undertake the preparation of these lectures. 



