VARIATION UNDER NATURE 49 



From these remarks it will be seen that I look at 

 the term species, as one arbitrarily given for the sake 

 of convenience to a set of individuals closely resembling 

 each other, and that it does not essentially differ from 

 the term variety, which is given to less distinct and 

 more fluctuating forms. The term variety, again, in 

 comparison with mere individual differences, is also 

 applied arbitrarily, and for mere convenience' sake. 



Guided by theoretical considerations, I thought that 

 some interesting results might be obtained in regard 

 to the nature and relations of the species which vary 

 most, by tabulating all the varieties in several well- 

 worked floras. At first this seemed a simple task ; but 

 Mr. H. C. Watson, to whom I am much indebted for 

 valuable advice and assistance on this subject, soon 

 convinced me that there were many difficulties, as did 

 subsequently Dr. Hooker, even in stronger terms. I 

 shall reserve for my future work the discussion of 

 these difficulties, and the tables themselves of the pro- 

 portional numbers of the varying species. Dr. Hooker 

 permits me to add, that after having carefully read my 

 manuscript, and examined the tables, he thinks that 

 the following statements are fairly well established. 

 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 exist- 

 ence,' ' divergence of character,' and other questions, 

 hereafter to be discussed. 



Alph. de Candolle 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 a far more important circumstance) with different 

 sets of organic beings. But my tables further show 

 that, in any limited country, the species which are 

 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), 



