132 H. MØLHOLM HANSEN 
lowlands. These plants find the most favourable conditions of growth 
round the hot springs. 
The circling investigations closely confirm these results. The 
Å percentage of the formations is higher in the highland than in 
lowland tracts, and higher in North Iceland than in South Iceland. 
The same applies to the sub-groups, A 1 showing a steady decrease 
in quantity from the lowlands to the highlands: at Bjørk and 
Lækjamôt the average A 1 percentages are 12.1, at Lyngdalur the 
A 1 percentage is 9.1, and at Arnarvatnsheiöi it is 5.8. 
A 2 occurs more frequently in the highlands than in the low- 
lands, and more frequently in North Iceland than in South Iceland, 
this is the case too with A 3, only in an even more marked degree. 
The E sub-groups show similar relations. E 4 occurs with equal 
frequency in the highland and lowland tracts. E 3 occurs most 
frequently in the lowlands, especially in the south country. The 
same applies in even greater degree to E 2 and especially to E 1. 
Table 26 shows the numerical values and their variations accord- 
ing to altitude and district. 
Table 26 shows the distribution of the species groups 
in the scale of moisture. 
The A group shows the same depression on moderately moist 
soil as the chamaephytes; from Zone IV the A percentage shows 
an increase, both upwards in the mo and downwards in the myri. 
In Zone VII, the flöi, the A percentage reaches its lowest value. 
The individual sub-groups show different relations; while the 
A 3 group decreases steadily as we pass downwards in the scale 
from mo through jadar to myri, the reverse is the case with the 
two other groups, so that the increase of A in the lower section 
must be ascribed to A2 and A 1. These relations are most plainly 
illustrated in the lowland series: Bjork, Lyngdalur, and Lekjamét. 
The individual sub-groups of E play a very different part in 
the composition of the vegetation. E 4 occurs in the greatest quan- 
tity, then successively E 3, E 2, and E 1. 
While E 4 and especially E 3 must be said to prefer the damper 
section of the scale, the reverse is the case with E 2 and E 1 which 
only occur in the mo formations. In the Lækjamôt series, however, 
E 2 forms an exception to this rule, for, similarly to E 4 and E 3, 
this group increases with increasing moisture of the soil. 
Even if the 7 sub-groups cannot perhaps be said to form a 
continuous scale of adaptation to decreasing temperature, this is at 
