Bouyoucos, Transpiration of Wheat Seedlings as Affected etc. 
s 
The method consisted of cutting out four triangulär shaped 
pieces from the circumference of corks which fitted 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 enough 
cork to allow the fitting of seedlings 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 fco 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 pans, 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 
practiGally 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 soll or sand cultures were conducted in 
the paraffined wire baskets, also recommended by the Bureau of Soils. 1 ) 
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 exactlv the same amount of soil was added to 
x ) Loc. cit. 
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