Ill VARIABILITY OF SPECIES IN A STATE OF NATURE 77 



many large genera. As examples we may take the roses, the 

 brambles, and the willows as well illustrating this fact. In Mr. 

 Baker's Revision of the British Roses (published by the Linnean 

 Society in 1863), he includes under the single species, Rosa 

 canina — the common dog-rose — no less than twenty -eight 

 named varieties distinguished by more or less constant characters 

 and often confined to special localities, and to these are 

 referred about seventy of the species of British and continental 

 botanists. Of the genus Rubus or bramble, five British species 

 are given in Bentham's Handbook of the British Flora, while 

 in the fifth edition of Babington's Manual of British Botany, 

 published about the same time, no less th3.n fort i/ five species 

 are described. Of willows (Salix) the same two works 

 enumerate fifteen and thirtij-one species respectively. The 

 hawkweeds (Hieracium) are ecjually puzzling, for while Mr. 

 Bentham admits only seven British species. Professor Babing- 

 ton describes no less than thirty-two, besides several named 

 varieties. 



A French botanist, Mons. A. Jordan, has collected numerous 

 forms of a common little plant, the spring whitlow -gTass 

 (Draba verna) ; he has cultivated these for several successive 

 years, and declares that they preserve their peculiarities un- 

 changed ; he also says that they each come true from seed, 

 and thus possess all the characteristics of true species. He 

 has described no less than fifty-two such species or permanent 

 varieties, all found in the south of France ; and he urges 

 botanists to follow his example in collecting, describing, and 

 cultivating all such varieties as may occur in their respective 

 districts. Xow, as the plant is very common almost all over 

 Europe and ranges from Xorth America to the Himalayas, 

 the number of similar forms over this ^Wde area would prob- 

 ably have to be reckoned by hundreds if not by thousands. 



The class of facts now adduced must certainly be held 

 to prove that in many large genera and in some single species 

 there is a very large amount of variation, which renders it 

 quite impossible for experts to agree upon the limits of species. 

 We ^vill now adduce a few striking cases of individual 

 variation. 



The distinguished botanist. Alp. de Candolle, made a special 

 study of the oaks of the whole world, and has stated some 



