1859-1863] HARVEY'S CRITICISMS 165 



inserted a discussion on this subject in the foreign editions. 1 In Letter 1 10 

 no case will any organic being tend to retrograde, unless such 

 retrogradation be an advantage to its varying offspring ; and it is 

 difficult to see how going back to the structure of the unknown 

 supposed original protozoon could ever be an advantage. 



Page 13 of your letter: I have been more glad to read 

 your discussion on "dominant " - forms than any part of your 

 letter. I can now see that I have not been cautious enough 

 in confining my definition and meaning. I cannot say that 

 you have altered my views. If Botrytris \Phytophthord\ had 

 exterminated the wild potato, a low form would have con- 

 quered a high ; but I cannot remember that I have ever said 

 (I am sure I never thought) that a low form would never 

 conquer a high. I have expressly alluded to parasites half 

 exterminating game-animals, and to the struggle for life 

 being sometimes between forms as different as possible : for 

 instance, between grasshoppers and herbivorous quadrupeds. 

 Under the many conditions of life which this world affords, 

 any group which is numerous in individuals and species and 

 is widely distributed, may properly be called dominant. I 

 never dreamed of considering that any one group, under all 

 conditions and throughout the world, would be predominant. 

 How could vertebrata be predominant under the conditions 

 of life in which parasitic worms live? What good would 

 their perfected senses and their intellect serve under such 

 conditions ? When I have spoken of dominant forms, it has 

 been in relation to the multiplication of new specific forms, 

 and the dominance of any one species has been relative 

 generally to other members of the same group, or at least 

 to beings exposed to similar conditions and coming into 

 competition. But I daresay that I have not in the Origin 

 made myself clear, and space has rendered it impossible. 

 But I thank you most sincerely for your valuable remarks, 

 though I do not agree with them. 



1 In the third edition a discussion on this point is added in 

 Chapter IV. 



2 Harvey writes : " Viewing organic nature in its widest aspect, I 

 think it is unquestionable that the truly dominant races are not those of 

 high, but those of low organisation " ; and goes on to quote the potato 

 disease, etc. In the third edition of the Origin, p. 56, a discussion is 

 introduced denning the author's use of the term "dominant." 



