6 Bouyoiicos, Transpiration of Wheat Seedlings as Affected etc. 



Each basket within tlio sanic density, and each ^Toup of 

 ])askets representing* the various concentrations, botli in the saud 

 and soil cultures, contained at each tinie, exactly the same aniount 

 of sand or soil, and exactly the same percentage of nioisture content. 

 The nioisture content was brought up to the desii-ed point 1)y the 

 additioii of the nutrieut Solution, and tlien kept at that point 

 throughout the duration of the experiment, by the addition of 

 distilled water. 



All the experiments conducted at the diiferent ])eriods always 

 received the same density of the same complete nutrieut Solution. 

 The composition and preparation of the latter are shown l)elow. 



Total 56.0 grams 



These salts were dissolved in 10 liters of distilled ^vater. 

 In Order to avoid as much precipitation as possible, they were 

 dissolved in the following* manner and then mixed together. 



Ca(Nos)2 plus KCL dissolved in 3 liters of water. 



MgSOi plus FeaCSOi) 3 dissolved in 3 liters of water. 



K2HPO4 dissolved in 3 liters of water. 



They were then brought together and the volume made up to 10 liters. 



Even when the above precautions were taken, some preci- 

 pitation did take place and the Solution had to be liltered through 

 ordinary filter paper. The density of the filtrate was then deter- 

 mined by evaporating 50 cc. of the Solution and weighing the 

 residue. This gave 4500 parts per million. From this stock 

 Solution, the different densities needed for the experiments were 

 prepared. These various concentrations with their strength in P. p. m., 

 and in electrical resistance as determined by the Wheatstone bridge, 

 are shown herewith. 



Each experiment was continued for three weeks. During this 

 period, the daily development and general appearance of the plants, 



