80 THE ORIGIN OF SPECIES 



other as the variety. But cases of great difficulty, which 

 I will not here enumerate, sometimes arise in deciding 

 whether or not to rank one form as a variety of another, 

 even when they are closely connected by intermediate 

 links; nor will the commonly-assumed hybrid nature of 

 the intermediate forms always remove the difficulty. In 

 very many cases, however, one form is ranked as a vari- 

 ety of another, not because the intermediate links have 

 actually been found, but because analogy leads the ob- 

 server to suppose either that they do now somewhere 

 exist, or may formerly have existed; and here a wide 

 door for the entry of doubt and conjecture is opened. 



Hence, in determining whether a form should be 

 ranked as a species or a variety, the opinion of natural- 

 ists having sound judgment and wide experience seems 

 the only guide to follow. We must, however, in many 

 cases, decide by a majority of naturalists, for few well- 

 marked and well-known varieties can be named which 

 have not been ranked as species by at least some com- 

 petent judges. 



That varieties of this doubtful nature are far from 

 uncommon cannot be disputed. Compare the several 

 floras of Great Britain, of France, or of the United 

 States, drawn up by different botanists, and see what a 

 surprising number of forms have been ranked by one 

 botanist as good species, and by another as mere vari- 

 eties, Mr. H. C, Watson, to whom I lie under deep obli- 

 gation for assistance of all kinds, has marked for me 182 

 British plants, which are generally considered as varieties, 

 but which have all been ranked by botanists as species; 

 and in making this list he has omitted many trifling 

 varieties, but which nevertheless have been ranked by 



