2\i 



for that period. Letting the v?ord grov|rth represent the ^aV" 



t'f^'ul'":/' ;J33 to -^ich the given Irirxd of measurerrent re- 



fers fas increase in height, increase in leaf area, etc.), 

 these may he spoken as growth increments, 



a, 



The mean dily growth jr.crements and t'le mean dail'^ 

 climatic values for the respective periods have been express- 

 ed in terms of the corresponding average of all the periods 

 considered , for all exposed stations. This prccedure rentiers 

 all the values directly comparaoie . To obtain this unit for 

 any kind of value, all of the corresponding values fas all 

 2-week daily mean increments in height, for example, for all 

 exposed stations) 7-'ere sumnied, and the sum was divided by the 

 number of values summed. Then each individual value was di- 

 vided by the unit thus obtained. The data are expressed as 

 these ratio values, which will be termed relative values in 

 the following discussion. The absolute magnitude of the tmtt 

 thus used for exi^ressiri^ ea?H Virri r>f value is«of course. not 

 important; it is essential only that all comparative values 

 be expressed in terms of the same xmit. The unit here employ- 

 ed represents in every case simply the average of all similar 

 quantities that are used In the present study. If another 

 station had been employed, or if the season had been longer 

 or shorter at any station, the values of these comparative 

 units would have been different. The magnitudes of these 

 units thus depend to some extent upon the climatic condi- 

 tions encountered at the various s ;.c. x^ns in the simmer of 

 1914, to some extent upon the number and location of the 

 stations, to sc-ae extent upon the nature of the soil used in 

 this investigation, and to some extent upon the physiological 



