THE GENOTYPICAL RESPONSE OF THE PLANT 
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3 MATERIAL AND CULTURES OF SUCCULENT COAST 
FORMS OF MESOPHYTIC INLAND SPECIES. 
It is well known from works on ecology that certain species are 
described as dimorphous (WarminG, 1909), showing a halophytic form 
with succulent, thick leaves, and an inland form with thin leaves. It 
is also known (Bararın, 1876; LESAGE, 1890; BoopLe, 1904 etc.) that 
fleshiness, increased development of palisades, reduction of intercellular 
spaces, etc. might be readily induced in many species by watering 
with solutions of sodium chloride. From these facts it might seem 
plausible that the halophytic, succulent forms of ordinarily mesophytic, 
thin-leaved inland species have been called forth by the modificatory 
action of the salt on the plant when growing in saline soil. ; 
In order to test to what extent such forms are merely modifica- 
tions or hereditary, some species showing »dimorphism» in this cha- 
racteristic were brought under culture. The species to be dealt with 
at some length in the following are Solanum Dulcamara L., Matricaria 
inodora L., Leontodon autumnalis L. and Melandrium rubrum (Weig.). 
Garcke. 
A. SOLANUM DULCAMARA. 
Sets of this widely distributed plant have been collected in the inland 
and at different points on the east and west coasts. The inland series 
(coll. at Krageholm, Scania 1919 and at Stehag, Scania 1920) include 
plants (20 in all) with smooth and rather thin leaves. Fig. 75 h illustra- 
tes the anatomical structure of the inland leaf type as seen in the 
cultures in 1922. The thickness of the middle leaves has been found 
to vary between 193 u. and 245 u. The sets from the east coast of 
Sweden (from Geta, 1920 and Västervik, 1920) include plants with 
both hairy and smooth leaves. The leaves of this type are usually 
somewhat thicker than the inland type both in the natural habitat and 
in the cultures. The most remarkable type, however, is the one that 
inhabits the west coast of Sweden. The leaves of this type are more 
than twice as thick as those of the inland type and always more or 
less hairy. It is found on the exposed, rocky shore (in the upper 
supralittoral belt) from north-western Scania and north-wards. A 
series of 16 plants of this type from Hallands Väderö was brought 
under culture in 1919. These 16 plants have all retained their hairy 
and fleshy leaves, although the fleshiness is somewhat less in the cul- 
tures than in the natural habitat. One of the plants with very thick 
