13 Bouyoucos, Transpiration of Wheat Seedlings as Affected etc. 



These iigures sliow thc diiference in weicht per Single i)lant 

 among- the tliree different cultures. *It is vei\v evident that the 

 average dry matter of the Solution culture is greater than that of 

 the sand or soil, receiving the sanie dcnsitics of Solution, and that 

 of the sand cultures, is larger than that of the soil cultures. 



Summary. 



In the foregoing investigation an atteinpt was made 

 to study the effect of different densities of Solutions upon 

 the relative transpiration of wheat seedlings. The results 

 obtained may be summarized as follows. 



The transpiration per gram of dry matter of wheat 

 seedlings grown in Solution, sand and soil cultures con- 

 taining 4500, 2250, 750, 375, 187.5. 93.5 and 0.0 P. p. m. re- 

 spectively of a complete nutricnt Solution, increased in 

 every case with the decrease in density down to a cer- 

 tain point and then decreased with thefurther diminution 

 in concentration, while the actual dry matter produced 

 increased with the rise in density. 



This general run of the relative transpiration was 

 explained thus: The increase from the highest concen- 

 tration to that where the change occurs, was thought 

 might be due to the decreased osmotic pressure of the 

 Solution and to the decreased density of the cell sap; 

 while the decrease from where the change occurs to the 

 lowest density, was believed might be due tho the de- 

 creased stimulative action of the dilute Solutions. 



The relation of the density of the Solution to that of 

 the plant cell sap was tested experimentally and it was 

 found that the density of the latter increased with the 

 concentration of the former. 



The relative transpiration was greater in the sand 

 and soil cultures than in the Solution cultures receiving 

 the same densities of Solution, and greater in the soil 

 than in the sand cultures; while the actual dry matter 

 produced was larger in the Solution than in the sand or 

 soil cultures and larger in the sand than in the soil cul- 

 tures. 



Michigan Agricultural College, 

 East Lansing, Mich., U. S. A. 



Literature cited. 



Abbe, C, Relations between climate and crops. 1905. p. 69. 

 Breazeale, J. F., Nutrient Solutions and wheat cultures. (Science. 22. 1905. 

 p. 146-149. 



