PREFACE. 
mong the results achieved by Danish botanical research, two espe- 
cially aroused my liveliest interest, viz. W.Johannsen’s demon- 
stration of the fixity of the genotype (“the genotype of homo- 
zygotic organisms is normally just as “fixed in type” as e. g. chemical 
composition” (Arvelighed 1918, p. 102)), and C. Raunkier’s demon- 
stration of the distribution of the life-forms within the va- 
rious climatic zones (“even the most widely separated regions with 
entirely different floras in a floristic respect but with essentially the 
same climatic conditions for plant life show in the main the same bio- 
logical spectrum” (Livsformernes Statistik som Grundlag for biologisk 
Plantegeografi. 1908, pp. 68—69). 
From these two facts I, as an impartial observer, drew the con- 
clusion that in Nature the development of forms as sketched in 
“Livsform og Alder’ (Bot. Tidsskr. 40: 193—203, 1928) must in the 
last instance be regarded as a physico-chemical process, the 
simplest manifestation of which is to be found in the trans- 
formation of a chemical combination, such as e.g. that of 
H,0 from vapour through water to ice (the gaseous, liquid, 
and solid phases respectively) during progressively decrea- 
sing temperature. In this way the species should be chemi- 
cal combinations whose phases are their life forms. 
This, however, is merely a theory, the correctness of which is 
primarily determined by its fruitfulness as a scientific working hypo- 
thesis. Hence it was expedient to collect further material to illustrate 
the relation between form and environment. As assistant to Professor 
Raunkiær in his investigation of the preserved heath at Nørholm (in 
the summers of 1921—1924) I was fortunate enough to become ac- 
quainted with the zone formation around collections of water, to which 
the attention of botanists had already been drawn in "Vesterhavets Øst- 
og Sydkysts Vegetation” (Raunkiær 1889). At Nørholm Heath I was 
able to collect material to elucidate the amount of individual species 
and life-forms in the various zones of moisture, and thanks to financial 
The Botany of Iceland. Vol, III. 1 
