Bouyoucos, Transpiration of Wheat Seedlings as Aflfected etc. 17 



Mention has been made that tlie sand and soll cultures were 

 employed, first. to duplicate tlie Solution cultures; and secondly, to 

 see whether the different deusities of Solution would affect the 

 transpiration of the wheat seedlings in these media in the same 

 Order or in the same magnitude as in the water cultures. The 

 table below gives these data. 



Table IX. 



Difference in the Transpiration Per Gram of Dry Matter Among Solution, 



Sand and Soil Cultures. 



Density of Solution Groater Transpiration per Gram Greater Transpiration per Gram 

 in P. p. m. of Dry Matter in Sand Cultures of Dry Matter in Soil Cultures 



over Water Cultures over Water Cultures 



4500 14.6 141.1 



2250 10.7 169.2 



750 20.0 143.7 



376 8.9 129.2 



187.5 —10.8 146.6 



93.5 —21.1 181.7 



0.0 172.6 332.1 



Average 27.8 177.7 



This table shows the difference in the transpiration per gram 

 of dry matter between Solution and sand cultures and between 

 Solution and soil cultures, Solution cultures beiug taken as a Standard 

 in both cases. It will be seen that there is a significant diiference 

 among these comparisons. Both the sand and soil cultures tran- 

 spired more per gram of dry matter than the Solution culture, and 

 the soil culture transpired the most. The sand and the soil cultures 

 gave off 27.8 and 177.7 grams of water per gram of dry matter 

 respectively, more than the Solution culture. Evidently, the different 

 densities in the culture Solution diminished the magnitude of the 

 transpiration per unit of growth, more than in the sand and soil 

 cultures. 



One other interesting feature that may be worked out from 

 tables I, II and III, is the difference in the dry matter produced 

 between Solution and sand cultures, Solution and soil cultures, and 

 sand and soil cultures. The table below gives these data. 



Table X. 



Difference in the Dry Matter Produced Among Solution, Sand And Soil Cultures 



Density of So- Greater Growth in Greater Growth in Greater Growth in 



lution in P. p. m. Solution Cultures Over Solution Cultures Over Sand Cultures Over 



Sand Cultures ■ Soil Cultures Soil Cultures 



Grams Grams Grams 



4500 -.00331 —.00355 —.00024 



2250 —.00390 .00071 .00461 



750 .00146 .00658 .00512 



375 .00451 .00683 .00232 



187.5 .00435 .00482 .00047 



93.5 .00235 .00129 —.00106 



0.0 —.00152 —.00255 —.00103 



Average .00056 .00206 .00145 



Beihefte Bot. Centralbl. Bd. XXIX. Abt. I. Heft l. 2 



