1908] DACHNOWSKI—TOXIC PROPERTY OF BOGS I41 
BENNETT (I) is against aerotropism in roots. It follows, therefore, 
that results reported as due to lack of aeration in the bog sub- 
stratum are really due to toxicity. Under natural conditions the 
inhibiting effect is eliminated by aeration, a slow process of oxida- 
tion preventing the accumulation of injurious plant excreta in the 
te jaba from cultures of the central zone. Numbers as in text, p. 133: 
a and photograph by Miss FREDA DETMERS. 
However, on account of the great demand for oxygen, the 
sie a be carried on efficiently only near the surface. Beneath, 
active bodies are more plentiful in the dead material than in the 
oe. An undrained peat substratum, i. sass 
adi i. aimee more marked deterioration in development and per 
association and succession of plants than a drained habitat. 
soil, 
