18 
Bouyoucos, Transpiration of Wheat Seedlings as Affeoted etc. 
These figures show the difference in weight per single plant 
among the three different cnltures. It is very evident that the 
average dry matter of the solution culture is greater than that of 
the sand or soil, receiving the same densities of solution, and that 
of the sand cultures, is larger than that of the soil cnltures. 
Summary. 
In the foregoing investigation an attempt 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 f'ollows. 
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 nutrient 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 tlie 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. 
