58 SPECIES OF LARGE GENERA Chap. II. 



we shall see how this may be explained, and how the 

 lesser differences between varieties will tend to increase 

 into the greater differences between species. 



There is one other point which seems to me worth 

 notice. Varieties generally have much restricted ranges : 

 this statement is indeed scarcely more than a truism, 

 for if a variety were found to have a wider range than 

 that of its supposed parent-species, their denominations 

 ought to be reversed. But there is also reason to believe, 

 that those species which are very closely allied to 

 other species, and in so far resemble varieties, often 

 have much restricted ranges. For instance, Mr. H. C. 

 Watson has marked for me in the well-sifted London 

 Catalogue of plants (4th edition) 63 plants which are 

 therein ranked as species, but which he considers as so 

 closely allied to other species as to be of doubtful value : 

 these 63 reputed species range on an average over 6*9 

 of the provinces into which Mr. Watson has divided 

 Great Britain. Now, in this same catalogue, 53 acknow- 

 ledged varieties are recorded, and these range over 7*7 

 provinces ; whereas, the species to which these varieties 

 belong range over 14*3 provinces. So that the acknow- 

 ledged varieties have very nearly the same restricted 

 average range, as have those very closely allied forms, 

 marked for me by Mr. Watson as doubtful species, but 

 which are almost universally ranked by British botanists 

 as good and true species. 



Finally, then, varieties have the same general cha- 

 racters as species, for they cannot be distinguished from 

 species, — except, firstly, by the discovery of intermediate 

 linking forms, and the occurrence of such links cannot 

 affect the actual characters of the forms which they 

 connect ; and except, secondly, by a certain amount of 



