1909] 



DACHNOWSKl—BOG TOXINS 



401 



ency; deposited upon their surfaces are found numerous colored 

 bodies, as the result of the oxidizing action of the roots. The nature 

 of these bodies is still under investigation. A general decay of the 

 growing tips is noticeable, showing that the oxidizing action of the 

 plants upon the toxic substances went far toward decreasing their 

 harmful effect, but could not entirely overcome them. The effective- 

 ness of adding the insoluble solids proves, therefore, very conclusively 



Fig. 2. — Growth of wheat plants in various cultures of bog water. Numbers 

 ^ in Table V. 



that the source of the harmful condition must logically be looked for 

 ln the solution and not in the condition of the plants themselves. The 

 difference in the tops as well as in the roots of the plants from the 

 yarious cultures is very striking. The stimulation effect is less marked 

 m the solutions filtered through clay and humus, because of the 

 greater adsorptive power of these substances; yet the increase in the 

 ^een and dry weight of plants is relatively twice that in the untreated 

 b °g water while transpiration has increased almost tenfold. The 

 Produced materials have had their adsorptive action, but it is evident 



