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TABLE I. 
Bint | Number | | vaal Din | ‘Width of tie 
a | of exp. The leaf base in: of exp. starch strip. 
Se ee eS eer eee eee eee 
Dahlia Yuareszii | I 5 °/, CO? | 5 hours 3 mm. 
” pe II open air adt 2-3 „ 
„ (Cactus) Thuringia XVI a DO To 34 „ 
Aster macrophyllus V open air En 0,5 
Sisymbrium Alliaria VI Kd : Di fig hi tg 
je 2 X pe pe Be A 
Polygonum Bistorta VII : 2 as er 
Aesculus Hippocastanum VIII ” > ba OFS: ting 
pn Pavia IX si 7 SiGe 6.57: Wy 
Acer campestre X fe 5 40% Wee fe 
Sambucus nigra XII 21/,°/, CO? | Ik ns Zie 
" st XIII : s SS ty Yi 
Juglans regia XIV AE Fi Sy Liv 
Acorus Calamus XV 5 » tee (di, se 
Heliopsis laevis | XVII | ZU, Gs | a 
of the leaf the border was a zig-zag line, which often coincided with 
the presence of veins in the leaf. In those places the border-line was 
sharply defined. In Acorus alone this line was also straight, without 
clearly depending on the veins; in this case moreover, the border 
line was not sharp, but towards the apex the reaction became 
weaker by imperceptible degrees and soon disappeared completely. 
Since in these experiments the apex of the leaf was in a space free 
from carbon dioxide we must assume, that the starch strip had 
been formed at the expense of the carbon dioxide, which had been 
transported from the portions of the leaf nearer the base. 
The most plausible assumption now seemed to be the following: 
that the carbon dioxide which had been absorbed by the leaf base, 
had been conducted through the parts of the leaf under the mercury, 
and having arrived in the part of the leaf exposed to the light, had 
there given rise to the formation of starch. In order to test the 
validity of this assumption, comparative experiments were undertaken, 
in which the one leaf was placed with its base in air containing 
