TRANSPIRATION OF SUN LEAVES AND SHADE LEAVES 
OF OLEA EUROPAEA AND OTHER BROAD-LEAVED 
EVERGREENS. 
JosEerH Y. BERGEN. 
(WITH ELEVEN FIGURES) 
Tue structural differences between sun leaves and shade leaves 
of several species have been described in a classical memoir by E. 
STAHL." FR. JoHow has given an excellent summary of the adapta- 
tions of foliage leaves with reference to transpiration.?2, LEon DurouR 
has investigated many of the differences in the vegetative and the 
productive organs of phanerogams due to differences in the amount 
of light supplied to them.3 
The writer has not at present access to any tolerably complete 
collection of botanical periodicals, but neither in ALFRED BURGER- 
= bibliographys nor in such journals as were accessible has he 
been able to find mention of any paper which discusses experimentally 
vt Subject of transpiration in leaves of the same individual, some 
developed in the sun and others in the shade. It would seem that the 
— of the relative activity of sun leaves and shade leaves must 
eae of value. For such an investigation no leaves can be more 
of what 305 those of such evergreens as the Mediterranean species 
and their etd calls the si artlaubflora, Olea, Quercus I lex, Myrtus, 
during ae For it is evident that leaves which are active 
t period ‘ar . from one to several years, and which during all of 
({chntagy : respectively exposed to illuminations varying from 
may be expect °° per cent. of the total amount afforded by the sun, 
— ed to show far more notable differences in structure 
ite. Jenn ooh . - oder schattigen Standortes auf die Ausbildung der Laub- 
* Usher die oo 16: oes 1882. 
issen, Jahrb. ni einiger Eigenschaften der Laubblatter zu den Standorts- 
. iss. Bot. 15:—. 1884. 
Pot. Vi 5:31 ‘ne — sur la forme et la structure des feuilles. Ann. Sci. Nat. 
4 pete . 
Zeal Bor. Geist he Monographie der Transpiration der Pflanzen. Verhandl. 
1904) i n. 1887 and 1899. 
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