Measuring-apparatus for 



Statistical Investigations of Plant-formations. 



While the determination and limitation of the plant-climates 

 only depend upon a qualitative analysis of the flora, i. e. a deter- 

 mination of the species and of their life-form, the investigation of 

 formations requires quantitative analysis in addition to qualitative, 

 that is, it requires a determination of the valency of the individual 

 species, i. e. their share in the composition of the vegetation. Though, 

 from a theoretical point of view, we may be justified in concluding 

 that the valency of the species should be determined according to 

 their mass, yet this basis of calculation cannot be used, as it is 

 practically impossible; here, however, I shall not enter more fully 

 into the question as I have dealt with it elsewhere 1 , where I have 

 also explained more particularly the reasons why I have chosen to 

 determine the valency of the species by their degree of frequency 

 in the formation in question. Hitherto the degree of frequency has 

 been determined simply by estimation; this is, however, too un- 

 reliable a method when the intention is to make a trustworthy 

 basis for the comparative investigation of formations. I have sug- 

 gested that the degree of frequency of the species of a certain for- 

 mation should be determined by means of a certain number of 

 samples of a certain size taken at random ; I have been experiment- 

 ing with different sizes of samples and have arrived at the con- 

 clusion that as a rule Vio square metre is a suitable size for a 

 sample. 



By 



C. Raunkiær. 



1 Formationsundersøgelse og Formationsstatistik. (Botanisk Tidsskrift, 30. Bind. 

 København 1909). 



