The Botany of Iceland - 01.12.1930, Side 192

182
II. M0LHOLM HANSKN
consideration, the frequency of the species gradually decreases, i. e.
the distance between individuals grows greater and greater and at
last the species entirely disappears. This applies to all species. The
individual species may be distinguished with respect to the position
of the maximum in the scale, the magnitude of the maximum, and
the number of degrees in the scale which the species covers.
The proportional distribution of the species in a given scale has
proved the same wherever it has been more closely investigated.
The distribution of Raunkiær’s life-forms in the scale of ex-
ternal factors is the same as that of the individual species. The
sequence of the maxima of the life-forrtis in the scale of moisture
from the inost moist to the driest section is as follows: HH^G—*
H—^Ch^-(Th). This sequence occurs wherever conditions have been
closely examined and remains the same whether the succession is
determined by means of the number of individuals (frequency sum)
or the number of species.
In the scale of snow-covering, Ch occur in greatest quantity
in the “sections devoid of snow”, H in the opposite sections. These
conditions are repeated wherever the facts have been investigated,
and remain the same whether calculated by means of the number
of individuals or by means of tlie number of species.
The distribution of the species groups in the scales of external
factors would seem to open up new possibilities of determining the
factors which are active in the distribution of plants.
Fig. 1 is to be found on page 21, the others are printed on
plates I—XII.