506 BOTANICAL GAZETTE , [December 



r m 



Now that it has been possible to show the inadequacy of 

 various of the physical environmental relations of plants in bogs 

 to account for the failure of some of the agricultural plants to thrive 

 and for the survival of others; and since differences in light-intensity, 

 in special absorptive powers of roots for peaty substrata, in fungal 

 mycorhiza, and in morphological limitations in the absorption and 

 in the conduction of water do not enter into the problem with the 

 agricultural plants used for the test experiments, it seems timely to 

 consider in more detail the specific role of the organic decomposition 

 products in the relation between the required quantity of available 

 water and the quantity absorbed by the plants. 



That some sort of regulatory, reciprocal mechanism, acting 

 within certain limits, is of the utmost importance in these species 

 seems evident from the fact that while the presence of structural 



* 



modifications is generally regarded as reaction in favor of a bog 

 vegetation, the most noteworthy characteristic which enables 

 invading plants to resist the unfavorable conditions is a greater 

 elasticity of functions and perhaps some specific place function. 

 What is the mechanism connected with the failure of many agri- 

 cultural plants to thrive in peat soils and in solutions of bog 

 water? What critical features, either as products of habitat or 

 congenital variation, do the surviving plants possess to regulate or 

 control the absorption of injurious organic bodies, and what are 

 the pathological aspects which involve dwarfing, leaf-fall, and 

 general senescence in most invading species alien to the habitat? 

 A knowledge of the limits of functional variation within a 

 known species and its several varieties should prove very essential 

 as to the role and the range of the individual and genetic differences 

 in the plants themselves, and the ability of the plants to inhibit 

 the absorption of deleterious bodies, or to neutralize the injurious 

 action of the substratum. 



In the present preliminary paper data are submitted which 



were obtained from experiments 



several 



standard varieties of grain sorghums, alfalfa, and bean. The 

 seeds were obtained from the United States Department of Agri- 

 culture through the office of seed distribution. The seeds were 

 germinated in sterilized quartz sand and employed in a manner 



