328 AMERICAN JOURNAL OF BOTANY [Vol. g, 



3. The absolute weight of green material, dry raatter, and ash was 

 determined for the tops, roots, and total plants in each culture. The ash 

 content was expressed in percentage of green weight and dry weight. 



4. The effects of reduced transpiration upon the total ash content of 

 the plants used in these experiments depended upon how transpiration was 

 reduced. 



5. Under the conditions of these experiments, with a uniform concen- 

 tration of nutrient solution, the total ash content of barley plants varied 

 but slightly even though the quantity of water transpired was reduced to 

 less than one half by increasing the atmospheric humidity. On the other 

 hand, in plants in which the transpiration was reduced to less than one 

 half by shading and the photosynthetic activity was also reduced, thus 

 reducing the available food, the total ash content was also correspondingly 

 reduced. When the total transpiration was reduced by increasing the 

 concentration of the nutrient solution, the total ash content was only 

 slightly reduced. 



6. The ash content expressed in percentage of total dry weight of the 

 whole plants varied but slightly, regardless of whether the plants were 

 grown under conditions of high or of low transpiration and irrespective of 

 how transpiration was reduced. 



7.. These results do not support the theory that transpiration has an 

 important role in supplying plants with nutrient salts. The results of this 

 investigation seem to indicate that, there being no other limiting factor, 

 the amount of food available which would allow for growth, in which process 

 nutrient salts are used, is an important factor in determining in how large 

 quantities or how rapidly the essential salts enter the plant. Analyses for 

 ash content indicate that there is little or no relation between transpiration 

 and the absorption of salts in barley plants. 



This investigation was suggested by and conducted under the direction of 

 Professor O. F. Curtis, to whom the writer is indebted for helpful advice 

 and a constant interest shown throughout its progress. 



Laboratory of Plant Physiology, 

 Cornell University 



LITERATURE CITED 



Burgerstein, A. Ueber die Transpirationsgrosse von Pflanzen feuchter Tropengebiete. 



Ber. Deutsch. Bot. Ges. 15 : 154-165. 1897. 

 /Curtis, O. F. The upward translocation of foods in woody plants I. Tissues concerned 



in translocation. Amer. Jour. Bot. 7 : 101-124. 1920. 

 Fittbogen, J. Untersuchungen uber das fur eine normale Production der Haferpflanze not- 



wendige Minimum von Bodenfeuchtigkeit sowie uber die Aufnahme von Bestand- 



teilen des Bodens bei verschiedenen Wassergehalt desselben. Landw. Jahrb. 2 ; 



252-371. 1873. 

 Giltay, E. Vergleichende Studien iiber die Starlce der Transpiration in den Tropen und in 



mitteleuropaischen Klime. Jahrb. Wiss. Bot. 30 : 615-644. 1897. 



