76 DARWINISM STATED BY DARWIN HIMSELF. 



have every reason to believe that many of these doubtful 

 and closely allied forms have permanently retained their 

 characters for a long time ; for as long, as far as we know, 

 as have good and true species. Practically, when a nat- 

 uralist can unite by means of intermediate links any two 

 forms, he treats the one as a variety of the other ; rank- 

 ing the most common, but sometimes the one first de- 

 scribed, as the species, and the 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 variety of another, not because the 

 intermediate links have actually been found, but because 

 analogy leads the observer 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 naturalists 

 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 competent 

 judges. 



That varieties of this doubtful nature are far from 

 uncommon can not 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 varieties. Mr. H. 



