8 ABSORPTION AND EXCRETION OF SALTS BY ROOTS. 
melted paraffin (melting point 65°) on the surface of the water to 
make a layer 7 or 8 mm. thick. After this layer had cooled and had 
drawn away from the sides of the beaker it was covered by a second 
layer of soft paraffin (melting point 45°) as thick as the first. The 
Fic, 1.—Seedlings of culture 4, experiment C. 
hard paraffin afforded the necessary rigidity; the soft, which adhered 
to the glass, served to hold the cake firmly in place. Holes about 
5 mm. in diameter were bored through the paraffin support. Four 
holes were equally spaced from the sides of the beaker and a fifth one 
was bored against the glass to serve as a pour-out. 
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