Bouyoucos, Transpiration of Wheat Seedlings as Affected etc. 5 



The method consisted of cutting out four triangulär shaped 

 pieces from the circumference of corks which iitted the mouths of 

 glass bottles black painted, of a capacity of 120 cc. The apex 

 of each cork piece was then truncated by the removal of enoug'h 

 cork to allow the fitting- of seedling's between the inner angle of 

 the slit and the cork piece. Four equally sized and vigorous wheat 

 seedlings were then fitted into the slits of each stopper with their 

 seeds just below the latter, and a rubber band was placed around 

 the cork to hold the pieces in place. The pieces exerted enough 

 pressure on the seedlings to hold them in their respective positions, 

 but not too great to interfere with their growth. The stopper 

 containing the plants was then pressed firmly into the neck of the 

 bottle which was filled with Solution nearly up to the seeds of the 

 plants. The seedlings employed were first germinated in moist 

 sand contained in paus, and allowed to reach the height of about 

 one inch before they were removed from the sand and transferred 

 into the Solution. 



In pulling out the seedlings from the quartz there was some 

 danger of damaging their tender and delicate roots if the quartz 

 was too dry, but if it was very wet there was no such danger. 



The culture Solution prepared as described above allowed 

 practically no direct evaporation from the Solution but only through 

 the exposed surfaces of the plants. Occasionally, when the cork 

 Stoppers became moistened by the layer of concentrated Solution 

 held around the wall of the mouth of the bottle by surface tension, 

 a rapid evaporation would take place through the corks by ca- 

 pillarity. The loss of water in this manner was easily prevented 

 by dipping the stoppers, after the slits were cut around them, into 

 melted paraffine, and the holes under the pieces were then opened 

 by a thin wire, just large enough to fit the seedlings. The thin 

 layer of paraffine formed around the stopper not only closed the 

 pores of the latter but also prevented the direct communication 

 between the stopper and the Solution when they were in direct 

 contact with each other. 



The cultures were weighed at intervals of three to four days 

 and the loss in weight was taken as a measure of transpiration, 

 The decrease was replaced at each time with the Solution, and 

 about once every week the entire Solution was changed. In this 

 manner the entire root System was constantly kept covered with 

 the Solution, and the Stagnation or any inequality in concentration 

 in the latter was avoided by its frequent renewal. 



The tests for the soil or sand cultures were conducted in 

 the paraffined wire baskets, also recommended by the Bureau of Solls, i) 



The baskets used for this work were about three inches deep 

 and three inches wide. Those in which soil was added were pre- 

 pared by repeated dipping the rim about one inch in height in 

 melted paraffine, with the intervening cooling in water until a firm 

 wall was formed. Then exactly the same amount of soil was added to 



1) Loc. cit. 



