Char VII] COLD TEMPERATE FOREST FORMATIONS 561 



With L=i (I max. = 1-250; I med. = 0-598) thick bright green leaves developed, the 

 dimensions of which averaged as follows : — 



Petiole ...... 29 mm. 



Length of blade . . . . . 18 ,, 



Breadth of do. . . . . . 29 ,, 



With L=$ (I max. = 0-317 ; I med. = 0-167) leaves developed of thoroughly normal 

 size and dimensions: — 



Petiole averaging ..... 



Length of blade ..... 



Breadth of do. . 

 With L = i (I max. = o-i58 ; I med. = 0-082) the same, viz. 

 Petiole averaging ..... 



Length of blade ..... 



Breadth of do. ..... 



With L =jV (I max. = o-o66; I med. = 0-038) the petioles were already visibly 

 abnormally long and the blades reduced in size. 



Most striking was the etiolated character of the experimental plants with L=-£t 

 (I max. = 0-039; I med. = 0-019), when the petiole attained a length of 145 mm., but 

 the lamina averaged only 22 mm. in length and 32 mm. in breadth ; the upper surfaces 

 of the pale green leaves were strongly concave. 



In the dark the petioles had attained an average length of 174 mm., whilst the 

 measurements of the lamina, which contained no chlorophyll, were only 11 and 

 17 mm. 



From the same author we again borrow the following data regarding the conditions 

 of illumination of the shade-plants of Central European forests : — 



Cynanchum Viuceto.xicitm. Grows in the open with h = ^-^ (I max. = 1-0-045) ; 

 is already visibly languishing with ^Va^- Flowers with L = ^-2 1 .7 (I max.= 1-0-068) ; 

 with ^j-oV already blossoms poorly. 



Convallaria midtiflora. Leaf development with L = jL-J. Flowers with L = 



JL 3L 



10 14" 



Prenanthes purpurea. Luxuriant growth and flowering with L (med.) = T 1 g (I med. 

 = 0-099-0-033). With L (med.) = 217-^ (I med. = 0-055-0-037) has defective flowers or 

 none at all. 



Corydalis cava : L=^-L Anemone nemorosa: L (med.) attains^; I med. = 0-089. 

 Only to L (med.) = .^- is the plant luxuriant, with L (med.) = i it appears only poorly 

 developed and no longer healthy. Sisymbrium Alliaria : L = J- T l r . 



The broad- leaved summer-forest differs from the rain-forest not only in 

 its general appearance, but also in the appearance presented by its individual 

 constituents, so far as the features can be shown to depend upon climate. 

 Summer-green trees exhibit a typical tropophilous character in the combi- 

 nation of the xerophilous habit of their perennial members with the hygro- 

 philous habit of their foliage. Trunks and boughs are covered by a thick 

 coat of cork, which in old age becomes deeply fissured by the formation of 

 bark ; resting buds arc enclosed in hard scaly cataphylls, and are also 



SCHIMPER Q O 



