— 403 



I); but it was not the typical West- Jutland maritima. The indivi- 

 duals were all grandifol, n.atropurp. The only maritima character, 

 they were in possession of, was caespitosa. Finally the whole 

 population had pallida petals. Both tricolor and arvensis lives 

 on Samsø (populations S, U, table I). 



IX. The Distribution after the Conditions of the Habitat. 



One of the most interesting facts concerning the distribution 

 of the isoreagents is that the isoreagents belonging to V. tricolor 

 maritima (parvifol, carnosula) have never been found in other 

 places than the dunes. 



Another interesting fact is the distribution of the isoreagents 

 according to the degree of acidity in the soil. Previously Ferdi- 

 nandsen (1918) has stated, that V. tricolor is acidophilous and he 

 suggests its possible occurrence on ground that lacks lime to 

 86 per cent. The corresponding index for V. arvensis he states to be 

 40 per cent., so that this species should be faintly acidophobous. 

 Ferdinandsen has recorded tricolor or arvensis from 31 of his 

 statistic tables (31 habitats). He classifies the degree of acidity 

 in the soil in the following classes: basic, faintly basic, neutral, 

 neutral-faintly acid, and acid. In the basic classes only arvensis 

 is found, in the classes neutral and faintly acid both arvensis 

 and tricolor and in the acid class only tricolor. The following table 

 shows the distribution of the habitats among the classes of acidity : 



Classes of acidity 



Reaction of soil 



basic 



faintly 

 basic 



neutral 



neutral- 

 faintly acid 



acid 



Number of 

 habitats with 



arvensis 



7 



3 



8 



5 





tricolor 







1 



4 



4 



Primarily it was not my intention to examine this question. 

 Therefore I was not prepared for a more detailed investigation. 

 But, during my journey, I observed that the distribution was 

 so characteristic that even a rather rough determination of the 

 degree of acidity might suffice to give a result. I applied litmus 

 paper, hence only a rough classification in basic, neutral and 

 acid was obtained. But this classification agrees with the general 



26* 



