— 395 — 



possible to place the individual, which is examined, under any 

 of the described systematic units. The result of these difficulties 

 is a multitude of new "species." The genus Hieracium is another 

 instance hereof. The increase of "species" in this genus has been 

 especially great in the last 15 years. The number of Hieraciiim- 

 names embodidied in the main volume of Index Kewensis is 

 about 1400. The increase has come as follows: 



In supplementum I, anno 1896 



— II, — 1901 



— III, — 1905 



— IV, — 1910 



— V, — 1915 



c. 900 species 

 40 — 

 40 — 



- 1800 — 



- 1200 — 



The number of "'species" up to the year of 1915 was about 

 5000, but it increases rapidly from day to day. Most of the new 

 "species" are Scandinavian. The diagnoses are very long and 

 comprise a 40 — 50 characters each. And I am sure there are 

 millions of '"species" not yet described. In Hieracium each little 

 character is fixed by apomixis, but there is no doubt (according 

 to Rosenberg's and Ostenfeld's investigations) that the different 

 types and the large variety is due to preceding crosses between 

 older species. Apparently circumstances here are to some extent 

 parallel to Viola. 



It is quite clear that this course leads to chaos. 

 On the other hånd we cannot be content with the old 

 division in species. In many accurate scientific investigations, 

 for instance in the relation between the piants and the habitat, 

 it is necessary to work with far smaller and more accurate limited 

 systematic units than those of the old ""Linnean" species. But 

 for these investigations, where sometimes one and sometimes 

 another combination of characters is needed, it is necessary to 

 work with the single, genotypically conditioned characters 

 and their combinations (i. e. the isoreagents), which can be placed 

 in a Schedule as the tables I and II (pag. 378 and 381). Millions 

 of new names of species are not needed for that reason. 



Even if we cannot state the reason for it, we feel sure that 

 there is a reality behind the notion of the Linnean species, in the 

 same manner as the genera are a reality. The Linnean species 

 become a superior classification above the new ""species" (varieties, 

 microspecies and isoreagents) just as Genus is a superior class- 



