HYDROHARMOSE Ill 
repotted in a loose sandy soil often enough. This permits the root system 
to develop normally, and also makes it possible to wash the soil away with- 
out injury to the root. The method is so recent that there has been 
no opportunity to test it in the field. It would seem that it can be applied 
without essential change to plants in their normal habitats. Very large 
herbs or plants with extensive root systems could not be used to advantage, 
and to be practicable the experiments would need to be carried on near the 
base station. The great value of the method, however, lies in its use as a 
check in determining the accuracy of other methods, and in practice it will 
Fig. 31. Absorption and transpiration of Helianthus annuus. Land 
Il, meni repotted in soil of known weight and water-content; III, 
plant undistured in the original soil; IV, potometer containing plant 
with cut stem; V, potometer with entire plant. 
often be found convenient and time-saving to use the latter, after they have 
once been carefully checked for different groups of species. This matter is 
further considered under measures of transpiration. 
156. The quantitative relation of absorption and transpiration. Bur- 
gerstein? has summarized the results of various investigators in the state- 
ment “that between the quantitative absorption of water on the one hand 
and emission on the other there exists no constant parallelism or proportion,” 
1Die Transpiration der Pflanzen, 14. 1904, 
