77 
tioned frequently already, it might suffice when, as in the present 
paper, we are considering the anatomy of the plants, to point out 
how far the light-assimilatory tissues and the power of protection 
against the danger of excessive transpiration have been developed. 
In regard to these points the climatic factors will at any rate be of 
importance. All these studies should, however, always be followed by 
investigations into the influence other climates may possibly have on 
the plants in question. 
It is with these points in view that I have taken up the present 
work. I am well aware that no definite result as to the influence 
of the climate on the Arctic plant-world can be arrived at merely 
by the study of the families treated here. Neither am I an authority 
upon Arctic climatology. I have only tried to explain the different 
types of adaptation and place them in their mutual relation to each 
other. I have attempted as far as possible to investigate the older 
Arctic forms, and the length of time the individual species have been 
in the Arctic region; but I have not succeeded in arriving at any 
definite conclusion regarding this point. In this connection I have 
been content to refer to the different geographical distributions. 
I shall return to this subject at the end of this paper. 
The material at my disposal has not been of much service in 
regard to comparison with other climates. Generally, Danish speci- 
mens, wherever they occurred, have been compared with those 
from the Arctic regions. But there was one great drawback in 
regard to the Danish (North European) as well as the Arctic 
material — it was too scanty. It is obvious that in ample material 
all the variations of a plant are more likely to occur than in scanty 
material. By having only a few specimens for investigation there 
is a possibility that too great importance may be attached to varia- 
tions which occur but seldom. It would have been possible for me 
to determine the variations which occurred in the material I had 
at my disposal, but owing to the fact that the habitats have not 
been recorded, it would have been impossible for me to enter into 
the reasons for the different variations; hence, 1 have not discussed 
them more fully. 
I cannot say that I have brought to light any particularly new 
and interesting facts; the subject has been too often dealt with in 
regard to its main points to allow of that. The value of the present 
paper lies principally in the fact that a great deal of information 
regarding these plants has here been collected, and that the individual 
