PERIODICAL LITERATURE 1001 



meters per year. Provided Germany is unable to pay in money, a pay- 

 ment in raw wood may not prove so chimerical, although such a cut 

 would deplete German growing stocks. Huffel also summarizes the 

 resources of "Austria." 



T. S. W., Jr. 



Bulletin de la Societe Centrale Forestiere de Belgique. July, 1919, pp. 172-179. 



SOIL, WATER, AND CLIMATE 



McLean has made a study of the effect of 



Studies in the certain habitat factors on the tropical rain-forests 

 Ecology of Tropical of southern Brazil. The object in view in making 

 Rain-Forest the investigation was primarily the estimation 



with what exactitude might be possible of some 

 of the ecological factors included under humidity, and illumination 

 and ascertain so far as possible how these factors affected the vegeta- 

 tion, particularly the plants under the forest canopy, morphologically 

 or otherwise, in relation to the transpiration problem and the assimila- 

 tion problem. The instrumentation and methods employed were those 

 suggested as the study proceeded and that circumstances permitted. 



The study was conducted in the rich forest on the hills and in the 

 valleys round about Rio de Janeiro, southern Brazil. The article undei 

 review includes the introduction and Part I of the complete research. 

 Part II will be published in a later issue of the Ecological Journal. 



There is an excellent though not exhaustive account of the general 

 topography and climate of the region ; the data relating to climate were 

 for the most part compiled from the records of the national observatory 

 in Rio de Janeiro, and those of the "Horto Florestal," the government 

 cultural experiment station. The climatic data discussed relates pri- 

 marily to air temperature, atmospheric humidity, precipitation and sun- 

 shine. In the correlation of these factors with vegetation the author 

 develops a method for combining the records of the several climatic 

 factors in a single graph representing the variation-cycle of climatic 

 favorability. 



The more important conclusions the author draws from his detailed 

 study of humidity and illumination in their effect upon the transpiration 

 and assimilation problems are : 



(a) Under the peculiar climatic conditions prevailing within the undergrowth 

 of tropical rain-forest, practically isolated from the influence of external 

 changes, there is in general very slight transpiration and a correspondingly low 

 rate of aqueous evaporation. 



