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. 



Drained warm bog substratum 



Undrained cold 



Drained cold Undrained warm 



FIG. 1 6. Relative effects of drainage and reduced substratum temperature, on 

 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- 



