June, 1922] 



MUENSCHER — ABSORPTION OF SALTS 



319 



be discussed later. If the salts in the solution enter the plant with the 

 water and the entrance of the water is determined largely by the rate at 

 which it is transpired, then, for a given concentration of salts, the greater 

 the quantity of water transpired the greater will be the amount of salts 

 brought in by the water absorbed. Burgerstein (1897) stated that a grow- 

 ing plant must take up large quantities of water to supply it with the nec- 

 essary inorganic elements. Sorauer (1880) and Thom and Holtz (1917) 

 suggested that the greater the concentration of the nutrient solution the 

 smaller the quantity of it necessary to supply the plant with the necessary 

 amounts of nutrient salts. Sachs (1887), Pfeffer (1900), and Jost (1907) 

 implied a direct relation between transpiration and the absorption of salts. 

 The data presented in table i do not bear out any direct relation between 

 transpiration and the absorption of salts in barley plants grown in water 

 cultures. On the contrary, the data indicate that the salts enter 

 the plant independently of the rate of transpiration. 



Light-Shade Cultures 



Table 2 presents a summary of the data obtained from the cultures in 

 which transpiration was reduced by shading. The shaded plants had 

 slightly taller tops but were more slender and had fewer leaves than the 

 plants growing in the open sunlight. The shaded plants stooled very little 

 while the plants growing in the sunlight all stooled profusely. The roots 

 of the shaded plants were much shorter and had fewer branches than those 

 grown in the sunlight. The total green weight, dry weight, and ash weight 

 were reduced to less than one half in the shaded plants. The shading not 

 only reduced transpiration, but also reduced the photosynthetic activity of 



Table 2. Relation of Ash Content in Barley Plants to the Amount of Transpiration as 

 A^ected by a Difference in Light Intensity. Summer Series.' 

 Plants Grown 5 Weeks {August 4 to September 8, ipso) 



No. of cultures averaged. . . 

 Green weight per culture (gramsj 

 Dry weight per culture (grams) 

 Total ash content per culture 



(grams) 



Ash content (percentage of green 



weight) 



Ash content (percentage of dry 



weight) 



Total water transpired (cc.) .... 

 Water used per gram dry matter 



(cc.) 



Water used per gram ash content 



(cc.) :.... 



Plants 



24 

 7.20 



-5944 

 .1209 

 1.68 



20.34 

 400 



672.95 

 3,308.52 



