June, 1922] MUENSCHER — ABSORPTION OF SALTS 317 



distilled water every two or three days, and the solution was changed every 

 fifth day. At the end of five weeks all cultures were taken down and the 

 green weight, dry weight, and ash weight were determined for the tops and 

 roots of each culture. After the dry weights had been determined, the 

 tops and roots. were incinerated in an electric furnace to determine the total 

 ash content. The ashing was made at a low red heat for several hours: 

 This furnace carried a 'load of eight crucibles at a time. In order to reduce the 

 error due to the method of ashing, each load consisted of one crucible contain- 

 ing the tops and another containing the roots of one culture from each of the 

 four conditions under which the cultures were grown. 



Winter Series 



The materials and methods employed in the winter series were the same 

 as those employed in the summer series. The plants used in this series 

 came from the same lot of seed as was employed for the summer series. 

 Two solutions were used, one a dilute Knop's solution (0.07 percent) and 

 the other a concentrated Knop's solution (0.28 percent). After these cul- 

 tures had remained upon the greenhouse bench for one week, all those which 

 did not contain four healthy plants were discarded, and the rest were di- 

 vided into three groups and placed under the following conditions : 



e. Sunlight; dilute Knop's solution (0.07%) 



/. Shade tent; dilute Knop's solution (0.07%) 



g. Sunlight; concentrated Knop's solution (0.28%) 



These cultures were grown for five weeks, from January 19 to February 

 24, 192 1. During this time the water lost by transpiration was replaced 

 with distilled water every two or three days, and the solution was changed 

 every fifth day. At the end of five weeks the cultures were all taken down, 

 and the green weight, dry weight, and ash weight were determined for the 

 tops and roots of each culture. 



Data and Discussion 

 Summer Series 



Dry-Humid Cultures 



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

 which transpiration was varied by changing the atmospheric humidity of 

 the chambers in which they were grown. The plants in the humid chamber 

 were slightly taller and their leaves were slightly longer than those in the 

 dry chamber. The roots of the plants grown in the dry charr^ber were on 

 the average about six centimeters longer and branched more profusely 

 than those of the plants grown in the humid chamber. The total green 

 weight, was slightly greater in the plants grown in the humid atmosphere, 

 probably because of the greater quantity of water in their tissues. The 



