Chat. II. DOMINANT SPECIES VARY MOST. 63 



and relations of the species which vary most, by tabulatinj^ 

 all the varieties in several Avell-workcd floras. At first this 

 seemed a simple task ; but Mr. H. C. W^atson, to whom I am 

 much indebted for valuable advice and assistance on this sub- 

 ject, soon convinced me that there were many difficulties, as 

 did subsequently Dr. Hooker, even in strono^er terms. I shall 

 reserve • for my future work the discussion of these difficulties, 

 and the tables themselves of the proportional numbers of the 

 varying species. Dr. Hooker permits me to add that, after 

 liaviufT' carefully read my manuscript, and examined the tables, 

 he tliinks tliat the follo\\ing statements are fairly well estab- 

 lished. The whole subject, however, treated as it necessarily 

 here is with much brevity, is rather pcrplexin;T, and allusions 

 cannot be avoided to the "struggle for existence," "divergence 

 of character," and other cjuestions, hereafter to be discussed. 



Alphonse de Candollc and others have shown that plants 

 which have very wide ranges generally present varieties ; and 

 this might have been expected, as they become exposed to 

 diverse physical conditions, and as they come into competition 

 (which, as we shall hereafter see, is an equally or more im- 

 portant circumstance, with different sets of organic beings. But 

 my ta])les further show that, in any limited country, the species 

 winch arc most common, that is, abound most in individuals, 

 and the species Avhich are most widely diifused 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 flourishing, or, as 

 they may be called the dominant species — those which range 

 widely, are the most diffused in their own country, and arc the 

 most numerous in individuals — wln'ch oftenest produce well- 

 marked varieties, or, as I consider them, incipient species. 

 And this, perhaps, might have been anticipated; for, as varie- 

 ties, in order to become in any degree permanent, necessarily 

 have to struggle with the other inhabitants of the coimtry, 

 the species which are already dominant will be the most likely 

 to yield olTspring, which, though in some slight degree modi- 

 fied, still inlu^rit those advantages tliat enabled their parents to 

 become dominant over their compatriots. In these remai'ks 

 on predominance, it should l)e understood that reference is 

 marie only to those forms which come into competition Avith 

 each other, and more especially to the members of the same 

 genus or class having nearly similar habits of life. With re- 



