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 

 I'egard to its main points to allow of that. The value of the present 

 paper hes principally in the fact that a great deal of information 

 regarding these plants has here been collected, and that the individual 



