Chap. I] 



THE FORMATIONS 



'/o 



timber-forest I must estimate mucli lower'. ... If we glance over the results 

 obtained in the above paragraphs, we cannot help expressing the opinion that 

 -7/1 extreme coiiliiienlal climate is iiii/nvoiirable to Iree-growtli, iv/iich can only attain 

 Us inaximiiin development in a iiiaiitimc climate-.'' 



The woodland-climate in its various gradations and the grassland- 

 ;limate remain qualitatively the same in all the zones, but differ 

 ijuantitatively from one another, so that their elements can be expressed 

 uimericaliy only for each xonc treated separately. The meteorological 

 .ables on which the opinions here developed are based are therefore 

 elegated to a later part of this book ''. 



iv. METEOROLOGICAL TABLES. 



The number of districts for which really useful and complete mctcoro- 

 ogical observations, extending over prolonged periods, are available, is 

 lot yet considerable. Yet in reference to several regions, that are well 

 haractcrized both as regards their climate and vegetation, there are 

 dread}- data which are sufficient in both these respects as a foundation for 

 ;eneral conclusions. Meteorologists do not always take into consideration 

 11 the factors that concern the climatic knowledge of vegetation ; though 

 his is partly the fault of geographical botanists, who formerly made 

 ery modest demands on meteorology owing to their misapprehension 

 s to the significance of many climatic elements. 



A Table really fit for use from a phytogeographical standpoint should, in my 

 pinion, contain the following headings: — 



Longitude . 

 .itionsl . . . . 



Latitude 



LOCALITY . . 

 . . ; Altitude . 



Me.in Barometric pressure (only at higli 



Temperature. 



Rainfall. 



Relative 

 humidity. 



Mean Mean i Sunshine. I Strength Evapora- 



Hours. ' of wind. 



tion. 



(onths. I Mean Mean Amount. Days. 



Min. Max. Min. Max. 



in. . . 

 eb. . 

 ar. 

 S;c. 



can annual extremes 



The variations in the atmospheric pressure carefully noted bj' meteorologists 

 e devoid of significance to vegetation. Of the data regarding temperature, 

 ose of the daily minima and maxima are the most important, in fact quite 

 fficient. Records of the hours of observation are hardly necessary, since the 

 inima occur at night and the maxima during daytime. The former give us the 

 mperatures at which the processes of growth chiefly occur, the maxima are 

 pecially important as factors influencing transpiration. The mean diurnal 



' MiddendorfT, op. cit., p. 632. ■ Id. p. 640. •' See Part, III. 



