66 DOMINANT SPECIES VAEY MOST. [Chap. II. 



might co-exist, and both rank as independent species. 

 But we shall hereafter return to this subject. 



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, a^ain, in 

 comparison with mere individual differences, is also 

 applied arbitrarily, for convenience' sake. 



Wide-ranging, much diffused, and common Species vary 



most. 



Guided bv 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 nianv difficulties, as did 

 subsequently Dr. Hooker, even in stronger terms. I 

 shall reserve for a future work the discussion of these 

 difficulties, and the tables of the proportional numbers 

 of the varying specie-. Dr. Hooker permits me to add 

 that after having carefully read my manuscript, and 

 examined the tables, he thinks that the following state- 

 ments 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 existence," " divergence of 

 character," and other questions, hereafter to be discussed. 



