Chap. II. Dominant Species vary most. 



4. 



tabids he thinks that the following statements are fairly well esta- 

 b t is hed The whole subject, however, treated as it necessarily here 

 is with much brevity, is rather perplexing, and allusions cannot be 

 avoided to the "struggle for existence," "divergence of character, 

 and other questions, hereafter to be discussed. 



Alphonse de Candolle and others have shown that plants which 

 have very wide ranges generally present varieties ; and this might 

 have been expected, as they are exposed to diverse physical condi- 

 tions, and as they come into competition (which, as we shall here- 

 after see, is an equally or more important circumstance) with 

 different sets of organic beings. But my tables further show that, 

 in any limited country, the species which are the most common, 

 that is abound most in individuals, and the species which are most 

 widely diffused within their own country (and this is a different 

 consideration from wide range, and to a certain extent from com- 

 monness), oftenest give rise to varieties sufficiently well-marked 

 to have been recorded in botanical works. Hence it is the most 

 flourishing, or, as they may be called, the dominant species, — those 

 which range widely, are the most diffused in their own country, and 

 are the most numerous in individuals, — which oftenest produce 

 well-marked varieties, or, as I consider them, incipient species. And 

 this, perhaps, might have been anticipated ; for, as varieties, in 

 order to become in any degree permanent, necessarily have to 

 struggle with the other inhabitants of the country, the species which, 

 are already dominant will be the most likely to yield offspring, 

 which, though in some slight degree modified, still inherit those 

 advantages that enabled their parents to become dominant over 

 their compatriots. In these remarks on predominance, it should be 

 understood that reference is made only to the forms which come 

 into competition with each other, and more especially to the mem- 

 bers of the same genus or class having nearly similar habits of life. 

 With respect to the number of individuals or commonness ol 

 species, the comparison of course relates only to the members 

 of the same group. One of the higher plants may be said to be 

 dominant if it be more numerous in individuals and. more widely 

 diffused than the other plants of the same country, which live under 

 nearly the same conditions. A plant of this kind is not the less 

 dominant because some conferva inhabiting the water or some 

 parasitic fungus is infinitely more numerous in individuals, and more 

 widely diffused. But if the conferva or parasitic fungus exceeds its 

 allies in the above respects, it will then be dominant within its own 

 class. 



