igi2] DACHNOWSKI—BOG PLANTS 505 



in the water table of the lake. In such a mat differences in the rate 

 of the movement of water through peat soil do not exist, and hence 



em 



1 



of removal of water by plants. 



The chemical analyses of Ohio peat soils, the data of which 

 appear elsewhere, 7 show wide variations, but there is a certain 

 uniformity in the range. When a correlation between the chemical 

 character of peat and the respective bog vegetation unit is attempted 

 the well defined relations are these: 



In poorly decomposed bog meadow peat the percentage of 

 volatile matter is high, the percentage of fixed carbon, nitrogen, 

 and ash is low; the reverse is true for the well decayed peat sup- 

 porting a bog forest and deciduous trees. 



Peat soils from various plant associations in bogs contain the 

 essential mineral salts such as potash, phosphoric acid, and others, 

 in inconsiderable quantities — only a fraction of 1 per cent. The 

 salts, it seems, play only a minor role for protoplasmic activities, 

 and in the growth and ripening of bog plants. Tolerance and 

 resistance of plants to bog habitat is not an osmotic relation; it 

 cannot be related to a greater resistance to water absorption pro- 

 duced by high external osmotic pressure, nor, it seems, to the 

 lack of some one salt in the mineral content of the soil or in the 

 plants. The ash content of the wood of bog trees is less than 0.5 

 per cent, with an occasional maximum of about 1 . 5 per cent. 



The solubility of the coarsely fibrous peat from bog meadows 

 is less than that of peat in more advanced stages of decomposition 

 supporting genetically higher associations of plants. The quantity 

 of nitrites, nitrates, and ammonia is very small and yet amply 

 sufficient to support luxuriant growth. Practically all the sub- 

 stances in solution are transition products of proteins and carbo- 

 hydrates arising through the action of obligate microorganisms. 

 Bacteriological investigations have shown clearly the importance 

 of biological processes. As a source of food to the microorganisms 

 and in the nature of the organic compounds produced during the 

 partial digestion of the upper layer of the vegetable debris, the 

 substratum constitutes an efficient limiting and selective factor. 



7 Dachxovvski, A., The peat deposits of Ohio. Geol. Surv. Ohio, Bull. 16, 1912 

 (in press). 



