BOOKS AND CURRENT LITERATURE 



An Intensive Study of Soil and Climate. — Kraus has added an 

 extended paper 1 to the list of those in which he has described the vege- 

 tation and physical conditions of the vicinity of Wurzburg. The keynote 

 of this paper is found in the author's statement that "under natural 

 conditions one may find in the smallest areas an endless diversity of 

 chemically and physically distinct habitats." The paper is at once an 

 elaboration of this idea, and a contribution to the precise, as distin- 

 guished from the superficial, knowledge of the relation of plants to 

 chemically distinct soils. 



The region over which Kraus has worked, in the immediate vicinity 

 of Gambach, possesses three distinct geological formations: limestone, 

 red sandstone, and loess, each of which has given rise to its overlying 

 soil, with a certain amount of admixture in small areas. Determina- 

 tions were made of the percentages of carbonate (mainly calcium, but 

 partly magnesium) in the underlying rock, and in the soil at various 

 depths, discovering a decreasing percentage from rock to soil and from 

 deep to superficial soil. The lime content of the calcareous soils them- 

 selves was found to vary from 21 to 57 %, that of the silicious soils of 

 the red sandstone was found to never fall below 4 %, and to rise as high 

 as 22 %, whereas the loess soils were often free of lime. Many examples 

 are given of the great variation of lime content in closely adjacent 

 soils. For example, on a calcareous soil five samples were taken within 

 a 40 cm. square which varied from 18 to 40 %. Numerous examinations 

 were made of the earth surrounding the roots of plants, and the majority 

 of species were found to grow in soils with lime content ranging between 

 maximum and minimum amounts which were from 30 to 40 % apart, 

 although the total range was higher in some plants and lower in others. 

 A species of Pulsatilla was found on soils entirely lacking in lime, and 

 on others with 54 %; while Hippocrepis comosa was found on soil free 

 from lime and on soil with 69 %. A few species of plants were found 

 which grow only on calcareous soils, but show themselves able to do with 

 widely varying amounts of lime. Such plants as Calluna and Vaccin- 



1 Kraus, G., Boden und Klima auf kleinstem Raum; Versuch einer exakten 

 Behandlung des Standorts auf dem Wellenkalk. Pp. 184, pis. 7, Fischer, Jena, 191 1 . 



300 



