- 406 — 



of Tunø. Only parv, albid was found here. These plants were 

 particularly vigorous ; but the rye was weak and the soil distinctly 

 acid. I have never seen Viola with a larger assimilating surface 

 than these individuals. This fact was due to both the large leaves 

 and the extraordinarily large stipules. Leaf and stipules of one 

 of these plants is pictured in fig. 1 e, pag. 365. I presume that 

 these arvensis descended from stabilized segregation products of 

 crosses between tricolor and arvensis. V. tricolor lives on the island 

 too. The chromosome number was the usual in arvensis, namely 

 17, and the divisions were regular (fig. 6 a, pag. 385). 



Population U is from a sandy grass field at Koldby Kaas 

 on the island Samsø. The soil was distinctly acid and the grass 

 sparse. Only parv, albid was found and but few. In contradis- 

 tinction from the specimens from population T they belonged to 

 a small dwarf type. A characteristic feature was, that 13 of the 

 14 plants had palmatisect stipules as tricolor. Fig. 4 a, pag. 369 

 shows leaf, stipules and flower of offspring of one of these individu- 

 als, cultivated in the Botanical Garden this year. All the offspring 

 was dwarf and palmatisect. The chromosome number is not 

 determined yet. I am quite sure that this arvensis type is a segre- 

 gation product from a cross between arvensis and tricolor. 



The "sentiment", if we may say so, of an individual against 

 the degree of acidity in the soil is a physiological character pos- 

 sibly contingent on one or more factors. Usually these factors 

 are coupled with the factors that stipulate the size and the colour 

 of the petals. The two species have a different optimum as to 

 the degree of acidity, arvensis at a high p H -value and tricolor 

 at a lower one. It is not likely that these factors for a certain 

 optimum should be coupled absolutely with the factors for the 

 morphological characters. When the two species cross, we there- 

 fore should expect to get arvensis types (parv, albid) with optimum 

 at a low p H . (acidophil) and tricolor types (grand, viol) with opti- 

 mum at a high p H . (acidophob.) In some cases the preceding re- 

 combination of factors is manifested by the fact, that a morpho- 

 logical character has been separated from the complex of cha- 

 racters it usually is connected with. Such is apparently the case 

 with the population U, where the character palmata together 

 with the character acidophilo wshave possibly become separated from 

 the character-complex grand, viol and instead have been connected 

 with the character-complex parv, albid. 



