106 



eno- the relative value of dry v.eight is always less than the 

 relative vf lue of leaf area. The two latter stateTr.ents also apply 

 tiQ the plants of the Baltimore forest station. 



From the data presenteu in the preceeding pages, the follow- 

 ing conclusions may be drawn as to the relations between the 

 climatic conditions and the various growth processes* (IJ The 

 height of the plents, in so far as it is determined by the con- 

 ditions here dealt v.ith, seems to be influenced m^ainly by sun- 

 shine ana temperature, in the CFse of the exposed plents the tem- 

 perature seems to have r- preponderating effect with sunshine acting 

 secondarily. The effect of temperature is direct, high tempera- 

 tures accelerating growth in height and low temperatures retarding 

 it, while sunshine has an inverse effect, high values retarding 

 and low values accelerating the ster. elongation rate. In the 

 case of the plants under glass stem, elongation rate is relatively 

 high ana in the case of the plants of the forest station it is 

 relatively very high. The facts indicate that low sunshine in- 

 tensity produces some etiolation in all the plants and consi- 

 derable etiolation in those grown under conditions such thrt a 

 part of the incident light is absorbed before it reaches the 

 plants as is the case for the glass-covered plants enc. those 

 grown in the forest. (2j The relation apparently existing bet- 

 ween the dry weight of the plants (or the leaf-product which is 

 an index of dry v.eight in these plents; and the climatic condi- 

 tions here dealt with may be stated in the form 



r = ^LJliKih) 



i:i which the symbols have thr; meaning previous].y given. 



