JUNE 7, 1901. ] 
stomata carry on the usual function while 
others serve for the exudation of nectar.’ 
Fic. 2. Transverse section through a stoma and 
adjacent tissue of the nectary. 
It is, however, not clear how the test was 
applied, and we believe that in view of the 
facts the question of the function of the sto- 
mata may be decided upon other grounds. 
A very few of these which occur on the 
edge of the nectarial surface have the ap- 
pearance of air stomata, but by all odds the 
big majority have the characters above de- 
seribed, from which it appears that the 
guard-cells are in such cases quite function- 
less in opening or closing the entrance. 
Furthermore, the nectar when it is being 
secreted is so abundant that it must needs 
hinder completely the gas interchange at 
that time. That such interchange takes 
place later is almost certainly the case, as 
is indicated by the condition of the chloro- 
phyll-bearing cells of the gland. Nor does 
the immobility of the guard-cells call for 
remark, inasmuch as the amount of tissue 
involved in transpiration coincident with 
respiration is relatively so very small as to 
have no effect upon the turgor of the whole 
leaf. Stomata are absent from the rest of the 
petiolar surface, excepting that, as Potonié * 
has pointed out, they are present along two 
* Potonié H. Jahrb. des Konigl. bot. Gartens zu 
Berlin, 1 : 310-317. 1881. 
SCIENCE. 
887 
bands on either side of the morphological 
upper flattened side of the leaf-stalk, be- 
neath which the hypodermal stereome is 
absent, though elsewhere present except 
in the nectaries. The relation of these 
bands to the glands should here be pointed 
out. As just stated, the rachis possesses 
two such bands, which pass without dividing, 
each along the lower margin of one of the 
first pair of pinnae. The band lying along 
the upper margin of a pinna and that along 
the side of the rachis nearer the same and 
above its insertion arise at the same point. 
At this point lies the nectary. These rela- 
tions, which are exhibited in Fig. 3, a and 
b, are repeated at each fork in the frond. 
Fic. 3. a, lateral view of rachis showing the nec- 
tary and the stomatal bands, s; 0, diagrams?showing 
the distribution of the bands. 
Through these true pneumathodes, by reason 
of the anatomical relations just indicated, 
the gas interchange may easily take place 
between the glandular tissue and the air. 
On old dead fronds the nectarial stomata 
are so large as to be seen with the naked 
eye, from which fact the presence and ex- 
tent of the gland beneath may be deter- 
mined. 
Beneath the epidermis lies the glandular 
tissue extending to a depth of 1 mm. or 
a fraction more.” In a transverse section 
through fresh material, the extent of the 
same may be recognized by the deeper 
green color contrasting with the lighter 
color of the surrounding tissues. The cells 
are rounded in form, as described for 
