The soil and its influence has long been a subject of interest 

 and investigation. As early as 1836 Unger 1 studied its chemical 



I. linger F. Uber den Einfluss des Bodens auf die Vertheiiung des Ge- 

 acbae. Vienne 1836. Review. Ann. Sci. Nat. 8:11,75-93. 1837. 



nature, deciding that it was the all important factor in soil influ- 

 ence upon plant distribution. On the other hand Thurmann 1 



1. Thurman Jules. Essai phycostatique quant a 1'infl.uence des roehes soua- 

 jacents. Paris, 1849. Review. Ann. Sci. Nat. 12:111,335-343. 1849. 



in 1849 became the sponsor of the physical theory of soils as 

 influencing the distribution of plant societies. From its variety 

 of nature, and physical properties, the soil invites a variety of 

 conditions in regard to food, heat, and moisture content. Of 

 these factors it is perhaps the last whose influence is predomi- 

 nant in determining the physiognomy of plant societies. Upon 

 this basis, the water content of the soil, Thurmann (1849) P ro ~ 

 posed a classification which was more fully developed later 

 (1896) by Warming, 2 who divided plant societies into three 



2. Warming, E., Okologische Pflazen geographie. Knoblauch translation, p. 116 

 Berlin, 1896. 



classes, hydrophytes, mesophytes, and xerophytes, those plants 

 inhabiting respectively soils rich, medium, and poor in moisture. 

 The source of soil water is primarily the rainfall of the region. 

 Though we have no readings from Ktaadn, data from Mt. 

 Washington can not fail to be pertinent. High as these moun- 

 tains are they intercept moisture-laden clouds and precipitation 

 is almost daily (see Table IV) and frequently excessive. A high 

 precipitation is the result. (Cf. Tables V and VI). 



TABLE IV RAINY DAYS. 



26 



