326 Forestry Quarterly. 



A further contribution towards establishing 

 Bog the theory of "toxicity" of soils as explain- 



Toxins. ing unproductiveness, is furnished by Al- 



fred Dachnowski, based on experiments 

 with wheat plants in water cultures, conducted in the Botanical 

 Laboratory of Ohio State University. The importance of these 

 investigations into the cause of infertility, especially of bogs 

 and swamps, lies in the fact that these swamp and muck lands 

 are naturally rich in constituents needed for plant food, and yet 

 have seldom given satisfaction, even after drainage and addi- 

 tion of fertilizers. In another series of experiments on the 

 cause of xerophily in bogs, the author had come to the conclusion 

 that the inhibiting factors of a bog are, in part, the presence in 

 the soil water of injurious toxic substances, that this toxicity can 

 be corrected by various methods, and that plants grown in solu- 

 tions thus treated show not only accelerated growth and an in- 

 crease in transpiration, but also an increase in the green and dry 

 weight of organic matter. 



Other tests seem to indicate that the toxins are not merely 

 specific excretions from the roots and rhizomes of bog plants, 

 but probably are certain unstable bodies of the nature of organic 

 compounds excreted from the roots in the absence of oxygen, and 

 in heavy clay soils not adequately aerated. 



Following is the summary resulting from the present investiga- 

 tion, as stated by the author: 



"1. Many swamp and muck soils exhibit a sterility which can- 

 not be remedied by drainage or by the addition of fertilizers. 



"2. The sterility appears to be most marked where investiga- 

 tions on the physiological properties of bog water and bog soils 

 indicate a greater amount and activity of bog toxins. 



"3. The production of bog toxins is due to a number of physi- 

 cal and chemical factors. One can only conclude that the chemi- 

 cal constitution of bog water and bog soils at a given moment 

 conditions toxicity and that the excretion from roots and rhi- 

 zomes 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- 



