30 BOTANICAL GAZETTE [JANUARY 
root growth and absorption; (3) that a cold undrained bog sub- 
stratum is analogous to a dry warm soil in that both produce physio- 
logical drought; (4) that resin bodies, which are characteristic of the 
bog plants, may be produced by this environment in a plant which 
under favorable conditions is without them. 
‘Undrained cold 
. : ce | 
Drained cold Undrained warm 
16.—Relative effects of drainage and reduced substratum temperature, on 
Fic. 
Larix. From photographs. 
The seedling tamaracks, ten of which were cultivated in each of 
the four conditions just described for the Rumex, also showed con- 
siderable variation. Their relative development at the end of forty- 
