VI PREFACE. 



But while Books I. and II. are thus the more important, 

 and such chapters as " Hermaphroditism," " Parthenogenesis," 

 " Alternation of Generations," have only a subordinate and 

 comparatively technical interest, it will be seen that our theme 

 raises nearly all the burning questions of biology. Hence, for 

 instance, a running discussion and criticism of the speculative 

 views of Professor Weismann, to which their very recent intro- 

 duction to English readers^ has awakened so wide an interest. 

 At once of less technical difficulty, and in some respects even 

 wider issues, is the discussion of Mr Darwin's theory of sexual 

 selection, reopened by the other leading contribution to the 

 year's biological literature which we owe to Mr Alfred Russel 

 Wallace.! Besides entering this controversy at the outset of the 

 volume, we have in the sequel attempted to show that the view 

 taken of the processes concerned with the maintenance of the 

 species leads necessarily to a profound alteration of our views 

 regarding its origin, although the vast problems thus raised 

 necessarily remain open for fuller separate treatment. It is right, 

 however, to say that the restatement of the theory of organic 

 evolution, for which we here seek to prepare (that not of indefi- 

 nite but definite variation, with progress and survival essen- 

 tially through the subordination of individual struggle and 

 development to species-maintaining ends), leads us frankly to 

 face the responsibility of thus popularising a field of natural 

 knowledge from which there are so many superficial reasons to 

 shrink, and which knowledge and ignorance so commonly 

 conspire to veil. For if not only the utmost degeneracy be 

 manifestly connected with the continuance of organic species, 

 but also the highest progress and blossoming of Hfe in all its 

 forms, of man or beast or flower, it becomes the first practical 



Heredity." Oxford, 1889. f " Darwinism." Lond. 1889. 



