SPECIES OF LAIUfEE GENERA VARIABLE. 51 



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 commonness), oftenest 

 give rise to varieties sufficiently well-marked to have been 

 recorded in botanical works. Hence it is the most flourish- 

 ing, 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 

 predominence, it should be uhderstood that reference is 

 made only to the forms which come into competition with 

 each other, and more especially to the members of the 

 same genus or class having nearly similar habits of life. 

 With respect to the number of individuals or commonness 

 of 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 para- 

 sitic 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. 



SPECIES OF THE LARGER GENERA IN EACH COUNTRY 

 VARY MORE FREQUENTLY THAN THE SPECIES OF THE 

 SMALLER GENERA. 



If the plants inhabiting a country, as described in any 

 Flora, be divided into two equal masses, all those in the 



