June, 1922] 
MUENSCHER — ■ ABSORPTION OF SALTS 
This indicates a possible relation between the food supplied by the tops to 
the roots and the utilization of inorganic salts in root growth. The plants 
which were not shaded and had a greater food supply also had a relatively 
greater ash content in their roots. Table 10 presents the ratio of roots to 
tops for all cultures. The root-top ratio of dry weights increases in both 
Table 10. Ratio of Roots to Tops under all Conditions under which Cultures 
were Grown 
Td Dry weight of tops Tg Green weight of tops 
Rd Dry weight of roots Rg Green weight of roots 
Summer Series 
Td 
Tg 
Rd 
Rg 
Dry chamber 
(0.14% solution) 
5.4 
2.9 
Humid chamber 
(0.14% solution) 
5-5 
3-5 
(0.14% solution) 
4.2 
2.8 
Shade tent 
(0.14% solution) 
6.0 
2.9 
Winter Series 
Sunlight • 
(0,07% solution) 
5-1 
2.3 
Shade tent 
(0.07% solution) 
7.8 
2.4 
Sunlight 
(0.28% solution) 
5-5 
1-9 
series of the light-shade cultures where the food supply is increased by 
increased photosynthetic activity. 
If only one of the two above-described series of cultures were used, and 
the results obtained were attributed to only one factor, namely, a variation 
in transpiration, one might conclude either that there is a relation between 
transpiration and the quantity of salts absorbed or that there is not, de- 
pending upon which series of cultures one happened to choose. As a matter 
of fact, when transpiration was reduced by shading, the photosynthetic 
activity of the leaves was also reduced, thus reducing the food available for 
growth. With a reduction in growth, smaller quantities of mineral nutrients 
are used and therefore inward diffusion is slower. This probably accounts for 
the greater difference in absolute ash content between the plants grown in 
the sun and in the shade as compared with the slight difference between the 
plants grown in the dry and humid chambers. The fact that the per- 
centage of ash, based upon dry weight of the whole plants, varies but slightly 
in the plants grown in dry or humid atmosphere or in light or shade bears 
out the indication that in these cultures there is a relation between growth 
and the absorption of essential salts, regardless of the rate of transpiration. 
Summary 
1. All plants used in the experiments reported in this paper came from a 
pure line of barley. The cultures were grown for five weeks in Knop's solu- 
tion in quart jars under conditions of high and low transpiration. 
2. The transpiration rate was reduced by (i) increasing the atmos- 
pheric humidity, (2) reducing the light intensity, (3) increasing the con- 
centration of the nutrient solution. 
