302 CAIN, DE OLIVEIRA CASTRO, PIRES, AND DA SILVA 



has been made of it. Realizing the inherent variabihty of leaves of a single 

 plant, Raunkiaer devised only a small number of size classes that increase 

 geometrically, as follows: 



Leptophyll: Leaves up to 25 sq. mm. area 



Nanophyll: Leaves from 25 to 225 sq. mm. in area, the upper limit being 

 9 X 25 sq. mm. 



Mkrophyll: Area from 225 to 2,025 sq. mm. (20.25 sq. cm.), or 9- X 25 



Mesophyll: Area from 2,025 to 18,225 sq. mm. (182.25 sq. cm.), or 9^ 

 X25 



Macrophyll: Area from 18,225 to 164,025 sq. mm. (1,640.25 sq. cm.), or 

 9^ X 25 sq. mm. 



Megaphyll: Leaves larger than macrophyll, or 1,640.25 sq. cm. 



Because of the range of the size classes and the variations among leaves, 

 it seldom is necessary to make a highly accurate measurement of leaf area, 

 for it usually is obvious to which class a leaf belongs. Raunkiaer presented a 

 diagram of the class sizes that helps visual comparison and suggested that 

 tracings could be cut out of paper, weighed, and compared with paper of 

 known area and weight. The authors have devised a simpler system which 

 uses a rule of thumb that the blade area is two-thirds of the rectangular area 

 of length by width. This was found to be rapid and sufficiently accurate for 

 Raunkiaerian leaf-size classification. 



MucAMBO, Belem, Para. Our most extensive sample of rain forest for 

 which we have both life-form and leaf-size classification of the total flora is 

 at Mucambo. The property of the Institute Agronomico do Norte lies at the 

 eastern edge of the city of Belem, Para, and includes an extensive tract of 

 primeval rain forest of terra firme type of which Mucambo is a part. In an 

 easily accessible part of this forest Dr. Mur^a Pires, of the Institute staff, had 

 surveyed a 2-hectare plot in 20 contiguous strips of 10 X 100 m. On each 

 strip all trees of 1 dm. diameter or more were marked by metal tags bearing 

 consecutive numbers. When the authors first visited the sample plot in Sep- 

 tember, 1955, identifications were still continuing and Dr. Pires was in the 

 United States. We later obtained permission to carry on plant sociological 

 work on the plot and revisited it in January, 1956. Part II of this paper gives 

 the details, but the life-form and leaf-size work is summarized here (tables 

 15-17). 



In table 15 we find that the total flora of the 2-hectare plot (table 4) con- 

 tained 218 vascular species, of which true phanerophytes (trees and shrubs) 

 were 162 (74 per cent). Therophytes were found to be absent, and chamae- 

 phytes, hemicryptophytes, and geophytes were of insignificant numbers. Table 

 16 is based on the same data but is organized so that the lianas (28 species, 

 12.8 per cent) and the epiphytes (18 species, 8.2 per cent) are distributed 

 among the phanerophytic-height classes according to the maximum height at 

 which each species was observed, except for two species the height of which 



