Beginning Botany .- I want to tell you a little about my mode
of teaching botany to beginners. Before long I will send you a copy
of a lecture on this subject.
I set a student on the very start to studying some natural object,
as a plant, a seed, a flower, a vine. He is asked to state to the class
on the following day what he has discovered. One of the first points
is to teach him to see and to become reliable and independent. To
acquire this habit he is set to looking. To help him he is often asked
to compare two branches of different trees, or two flowers of different
species or genera, or two seeds or fruits.
I require students to write out more or less their observations.
For this work credit is given, as well as for class recitations. This is
not only done in the botany class, but our Professor of the English
language, finds such topics among the best he can select for the practice of young students. Many of the essays required are accompanied by
drawings which help to explain certain points. As an example of this
work, I send a short paper prepared by a member of the Freshman class.
It must be remembered that he is a beginner ; that he used no books,
but went to the plants to get his facts. He had been studying plants
for a few weeks. He had been referred to an elementary book for some
names. He had received some hints on some points from his teacher
while in the class room. Of course, he picked up more or less from
his classmates during recitations, in which they spoke of kindred
topics :
THE FERTILIZATION OF THE TRUMPET-CREEPER, BY GEORGE SPRANG .-
In the bud the calyx of the Trumpet-Creeper is valvate and encloses the other
organs of the flower; the corolla is deeply imbricated, and covers the stamens
and pistil.
The anthers of the young flower are very large and of a bright yellow;
they are composed of two mealy sacks which are slightly attached together
and fall back and nearly cover the filament.
As the flower grows and becomes larger, the anthers become smaller until
they are only about one-third of their original size.
In the bud the pistil is already quite tall and has to take a stooping position, but when the flower grows and opens the pistil takes an upright position
and always keeps above and out of the reach of the stamens.
Most flowers require crossing, and the arrangement of most of them is
such as to prevent self-fertilization and to insure crossing.
The above example is the most common mode by which self-fertilization
is prevented, but this plant has other and more striking illustrations of this
fact.
The stigma is two-lobed and is so sensitive that if anything touches it, it
immediately closes, hence, when the Humming-bird, the principal means by
which this plant is fertilized, hovers over the flower and sticks its long proboscis down into the tube its head touches these lobes and they close almost
immediately and remain so for a short time.
The anther cells are now open and ready to shed pollen, and as the bird
puts its head further down into the tube, it hits these cells and the pollen is
dusted upon it, and flying back it hits the pistil again but the stigma is closed
and none of the pollen can get in.
But when it goes into the next flower the stigma is open and the pollen is
shed upon its lips, sometimes so much as to be plainly seen by the naked eye.
This process is repeated till the bird, tired of the meagre amount of honey
it gets for is labors, flies to some other plant hoping for better success.
This plant has an enemy in the black ant which does not enter the flower
at the mouth, but eats through the calyx and corolla and sucks the honey which
is laid up for the attraction of the birds. Even if the ant did enter at the top
and get pollen upon it, it would immediately fall off from its smooth body
and legs and thus use up the pollen which would be of no use to the plant in
its fertilization.
But the plant's bright and gaudy corolla attracts the birds and even if one
does not enter more than two or three flowers, yet it enters enough to scatter
the pollen on some pistil and fertilize it.
It has often seemed to me that scientific magazines did not pay
enough attention to the best modes of teaching science.
PROF. W. J. BEAL,
Agricultural College, Lansing, Mich.