228 GÔTE TURESSON 
In summarizing the results of the cultivations it should be said 
that it might be safely assumed that the dwarf C. jacea f. humilis of 
the salt meadows is made up of a heterogeneous assemblage of 
most diverse, genetically different types. They all react upon the 
extreme habitat conditions with dwarf growth, thus giving the impres- 
sion of a homogeneous population just as in the case of the dwarf 
Succisa. — The question whether or not the erect Centaurea jacea of 
Fig. 9. Centaurea jacea. Behaviour of a dwarf series (no. 37) when cultivated. 
the inland might in nature become modified to the same extent has 
not yet been investigated. 
Additional dwarf forms, including those of Veronica spicata L. 
from sand dunes, Achillea millefolium L. from the same habitat, and 
Prunella vulgaris L. from salt meadows, have all upon culturing been 
found to be modifications presumably called forth by ‘insufficient 
water and food supply in the respective habitats (Jost, 1913; 
WITTE, 1906). 
