44 Elementary Species 



from one locality may be grown, and all will ex- 

 hibit exactly the same markings. Most of these 

 forms are of very local occurrence. The most 

 beautiful of all, the ornatissima, is found only in 

 Jemtland, the aurobadia only in Sodermanland, 

 the anopetala in other localities in the same 

 country, the roseola near Stockholm, and the 

 yellow lutescens in Finmarken. 



The researches of Wittrock included only a 

 small number of elementary species, but every 

 one who has observed the violets in the central 

 parts of Europe must be convinced that many 

 dozens of constant forms of the typical Viola 

 tricolor might easily be found and isolated. 



We now come to the field pansy, the Viola ar- 

 vensis, a very common weed in the grain-fields 

 of central Europe. I have already mentioned 

 its small corolla, surpassed by the lobes of the 

 calyx and its capacity of self-fertilization. It 

 has still other curious differentiating charac- 

 ters; the pollen grains, which are square in 

 V. tricolor, are five-sided in V. arvensis. 

 Some transgressive fluctuating variability may 

 occur in both cases through the admixture 

 of pollen-grains. Even three-angled pollen- 

 grains are seen sometimes. Other marks are 

 observed in the form of the anthers and the 

 spur. 



There seem to be very many local subspecies 



