x 9°9] DACHNOWSKI—BOG TOXINS 403 



SUMMARY 



The available information of the study here reported may be 

 summarized as follows: 



1. Many swamp and muck soils exhibit a sterility which cannot 

 be remedied by drainage or by the addition of fertilizers. 



2. The sterility appears to be most marked where investigations 

 on the physiological properties of bog water and bog soils indicate 

 a greater amount and activity of bog toxins. 



3. The production of bogs toxins is due to a number of physical 

 and chemical factors. One can only conclude that the chemical con- 

 stitution of bog water and bog soils at a given moment conditions 

 toxicity; and that the excretion from roots and rhizomes of plants 

 is one of the variables of the conditioning factors. 



4- In untreated bog water there are found deposited upon the 

 roots of wheat plants numerous colored bodies as the result of the 

 oxidizing action of roots. The general decay of the root-tips indicates 

 that the oxidizing activity is insufficient to decrease the harmful effects 

 of bog toxins. 



5- It is possible that ecesis, association, and succession of plants 

 depends primarily upon respiration, and that in respiration bog plants 

 differ from other plants. 



6. Treating bog water with an insoluble adsorbing agent is invari- 

 ably beneficial. 



7- Different physiological phases result from the progressive 

 addition of an adsorbing substance. With coarser-grained materials 

 the low optimum rate of transpiration is soon succeeded by a minimum 

 which is due to the action of toxic substances still present. 



8. Finer-grained insoluble bodies are more beneficial. The 

 response to toxic bodies when present in small amounts leads to 

 acceleration of growth. The period of growth is more prolonged, 

 a nd the optimum and maximum rate of transpiration lie near 

 together. 



9- The adsorptive action of carborundum and humus is about 

 |our times greater than that of quartz ; the capacity of soils for retain- 

 m g toxins is therefore higher the greater the content of humus. 



10. The decrease of the poisonous effect of bog water is probably 

 a Unction of the surface of the particles; it is relatively proportionate 

 t0 the quantity of the solid body used. 



