46 ON THE ORIGIN OF SPECIES 



considered by highly-competent judges as varieties, have 

 so perfectly the character of species that they are ranked 

 by other highly-competent judges as good and true 

 species. But to discuss whether they are rightly called 

 species or varieties, before any definition of these terms 

 has been generally accepted, is vainly to beat the air. 



Many of the cases of strongly-marked varieties or 

 doubtful species well deserve consideration ; for several 

 interesting lines of argument, from geographical dis- 

 tribution, analogical variation, hybridism, etc., have 

 been brought to bear on the attempt to determine their 

 rank. I will here give only a single instance, — the 

 well-known one of the primrose and cowslip, or 

 Primula vulgaris and veris. These plants differ con- 

 siderably in appearance ; they have a different flavour, 

 and emit a different odour ; they flower at slightly 

 different periods ; they grow in somewhat different 

 stations ; they ascend mountains to different heights ; 

 they have different geographical ranges ; and lastly, 

 according to very numerous experiments made during 

 several years by that most careful observer Gartner, 

 they can be crossed only with much difficulty. We 

 could hardly wish for better evidence of the two forms 

 being specifically distinct. On the other hand, they 

 are united by many intermediate links, and it is 

 very doubtful whether these links are hybrids ; and 

 there is, as it seems to me, an overwhelming amount of 

 experimental evidence, showing that they descend 

 from common parents, and consequently must be 

 ranked as varieties. 



Close investigation, in most cases, will bring natural- 

 ists to an agreement how to rank doubtful forms. Yet 

 it must be confessed that it is in the best- known 

 countries that we find the greatest number of forms of 

 doubtful value. I have been struck with the fact, that 

 if any animal or plant in a state of nature be highly 

 useful to man, or from any cause closely attract his 

 attention, varieties of it will almost universally be 

 found recorded. These varieties, moreover, will be 

 often ranked by some authors as species. Look at the 



