Democratic messenger. [volume] (Snow Hill, Md.) 1869-1973, 1905-11-25
SENSE ORGANS IN PLANTS.
Light Pcrrciving Leaves That Have
Eyer md EycInslles.

Light Pcrrciving Leaves That Have
Eyes and EycIashcs.
DR.. q. lIabcrlandt. professor Of bot
any IN the University of Gratz. ccle-
bratcd for his revelations on the sense
organs In plants. Is their champion
who tells the world that. having eyes.
obey see.
The first question for DIR. Haberlandt
to solve was what part of the leaf was
sensitive To light. by covering the
leaf with black paper he shows that
the principal and most delicate sensl-
tlvcnnss resides IN the blade. although
coarscr and secondary sensitiveness
to the incident light Is found In the
stalk
This meant that the blade OF the leaf
must contain the eyes. II eyes there be-
Anything corresponding to an organ
for sight. he reasoned. would be on
the surface. So he looked for the
occlli. as he terms the light perceiving
organs Of plants. In the cpl,lcrInis COW
erlng the upper surface Of the leaf.
II can also be seen, as the botan-
icnl oculist discovered. that the rcla-
ton of the spot of light TO the sur
rounding part. which is more or less
dark, changes when the light falls
obliquely. SO when a leaf Is illuminat-
ed obliqucly he considers that 1t Is
stimulated to curve by the fact that
the spots of light are not central In the
cells. and the curving ceases when the
brightest illumination Is once more In
the center. So the plasmic membrane
of this inner wall of each cell in the
epidcrmis becomes the rctina OF the
eye. or. in scientific phrase. has a
quasi retinal function by which the
leaf IL bclicrcd 10 orlentate itself In re-
gard 60 Fight"
Proceeding. Dr. Iabcrlandt exam
ined the eye and found that II was
good. well fitted TO concentrate light. II
Is commonly lcnslike In form. the outer
wall being convex, the inner wall ell
thcr plain or curved.
Plants have not only eyes. but eye.
laslles. The tropaeolum. the handsome
cousin of the ilorid fuchsia Is one Of
selves on the luxurious comeliness Of
fine lashcs. The leaves of this plant are
unwettablc. and when immersed re-
main coated with silvery mantle OF
air. The waxy layer which gives this
quality may be removed by painting
out injury 10 the leaves. The result OF
Immersion Is that normal leaves. pro-
tected by II layer of air. react normal
~ TO oblique illuminations-that Is,
they see. whereas the wettable leaves
whose waxy bloom has been removed
have lost their eyesight. their power Of
reacting. says the Chicago Tribune.
IN all Dr. Haberlandt's experiments
he always has found his ocelli (eyes) on
..thc upper and not the lower surface OF
leaves. And he also found them tend
ing 10 occur especially near the edges
of leaves just in those regions where
the amount of movement correspond.
ing tn curvature through II given angle
Is greatest.
The position of the eyes Is In the
most advantageous position possible
for the eyes TO receive the rays of the
sun and yet he shielded from exposure.
The cyelashes droop directly over the
eye itself when showers come. and the
leaf turns slightly so that the eyelashes
form perfect protection. Also. II the
leaf Is exposed 10 too great heat from
the sun the lashes droop again. shad-
Ing them.
The eyes of leaves vary greatly. ac-
cor,llng To the professor. In different
plants ana trees. and he believes the
sense of sight much more highly devel-
oped In the rapid growing and tropical
plants than In otllers.-New York
World.