332 GOTE TURESSON 
area. This is not the case. A field examination of 86 individuals from 
this zone gave the following classes: 8 more or less erect, 31 ascending, 
and 47 prostrate. A similar classification of 112 individuals within the 
drift-sand region proper (at Löderup) gave the following result: 44 more 
or less erect, 61 ascending, and 7 prostrate. An examination of 119 
individuals at Vitemölle, in the area of the arenacious fields, resulted 
in the following relations: 7 ascending, and 112 prostrate. The dif- 
ferent groups found in the population at Kylsgard substantiate the view 
that the intermediate zone between the areas occupied by the dune 
forms of the drift-sand and of the arenacious fields respectively is in- 
habited by fragments of these two types and, probably, by bastards 
between the two types. The population in question conforms to that 
which is to be expected in the case of hereditary forms meeting in a 
transitional belt. It thus confirms the statement to the same effect 
already made by Näcerı (1866), and also the opinion expressed by 
BATESON (1913) that in the area of intergradation of two hereditary 
types no uniformly intermediate population is found but, on the 
contrary, fragments of the two types together with mongrels be- 
tween them. 
It does not seem necessary to review once more the question of 
the hereditary nature of the types of different species distinguished 
above. The data collected from the cultural experiments furnish 
ample evidence of the hereditary differences between the different ty- 
pes. Certain characteristics usually common to all or to the majority 
of the individuals of a certain habitat have facilitated their grouping 
into habitat types, in spite of the hereditary differences seen between 
the individuals of the same type. ‘These habitat types may sometimes 
appear more homogeneously in the field than in the cultures, as has 
been shown to be the case with the Centaurea and Succisa dwarfs of the 
salt meadows as well as with the Hieracium population at Vitemölle 
(table 29). The masking of the hereditary differences between the indi- 
viduals of such types by the modifying effect of extreme habitat factors 
is readily revealed upon culturing the types. When, nevertheless, the in- 
dividuals of a type of a definite habitat so often appear to be »fixed» 
as to certain characteristics, the factor responsible for this fixity be- 
comes of great interest. 
To take refuge in the Lamarckian view of the origin of the charac- 
teristics in question seems wholly futile. It must suffice here to refer 
to the current handbooks (JOHANNSEN, 1913; Baur, 1914) for a full 
account of the difficulties met with when the attempt is made to make this 
