Plant I 7 pistils right-handed, 7 left-handed.
" II 6 " " 6 "
" III 8 " " 9 "
" IV 29 " " 31 "
" V 11 " " 7 "
" VI 10 " " 7 "
" VII 10 " " 13 "
" VIII 3 " " 3 "
" IX 3 " " 2 "
" X 6 " " 9 "
—— —— ——
Total 10 93 pistils right-handed, 94 left-handed.
So in these ten plants the number of right-and left-handed flowers is
practically equal. The greatest difference in the number of the two
kinds is seen in number X, where forty per cent. are right-handed and
sixty per cent. left-handed.
Considerable care was exercised in determining the number of right-and
left-handed flowers opening on the racemes of different branches at the
same time.
Only those flowers were considered which had opened simultaneously. In
order to effect this, all the flowers were removed from the plant the
evening before and note was made of the condition of those opening the
next day.
The following diagram shows the conditions of flowers opening on three
plants on the morning of August 20, braces indicating the branches of
the plant, and the straight lines the racemes; the numbers of right-
and left-handed flowers being indicated under the raceme by _r_ and
_l_. (See page 20.)
From the table, it will be seen that there are on the first plant 8
left-and 11 right-handed flowers; on the second, 24 left-and 27
right-handed; on the third, 7 left-and 9 right-handed flowers. The
numbers of right-and left-handed flowers occurring on the divisions
a and b of the main branches, A and B, of the three plants, are as
follows:
[Illustration]
I.-Aa, 2_l_, 1_r_; Ab, 1_l_, 3_r_; Ba, 4_l_, 4_r_; Bb, 1_l_, 3_r_.
II.-Aa, 8_l_, 13_r_; Ab, 13_l_, 11_r_; Ba, 1_l_, Bb, 1_l_; B, 2_l_, 3_r_.
III.-Aa, 4_l_, 2_r_; Ab, 2_l_, 1_r_; Ba, 3_r_; Bb, 1_r_; B, 2_r_, 1_l_.
On the three plants, with 36 racemes bearing branches, there were 18
branches which produced only one kind of flowers. Of these branches,
however, 15 bore only 1 flower each. From this it will be seen that the
flowers opening at the same time on any one branch are not all either
right-or left-handed. In the large branches, A and B, the number of
the two kinds is quite evenly distributed; in only one case-branch
B of plant III—is a large per cent. of the flowers alike. Even in
branches of the second denomination—Aa, Bb—flowers of one kind occur
exclusively, where more than one flower is found, only in Ba of plant
III.
In addition to the above table, observations were made on three plants
to determine the regularity with which they bore right-and left-handed
flowers. On three successive mornings the plants had produced:
═══════════════╤═════════════════╤═════════════════╤════════════════╕
│ I. │ II. │ III. │
├────────┬────────┼────────┬────────┼────────┬───────┤
│ Right. │ Left. │ Right. │ Left. │ Right. │ Left. │
───────────────┼────────┼────────┼────────┼────────┼────────┼───────┤
First morning │ 7 │ 7 │ 6 │ 6 │ 8 │ 9 │
Second morning │ 7 │ 11 │ 10 │ 7 │ 14 │ 17 │
Third morning │ 16 │ 10 │ 8 │ 12 │ 13 │ 10 │
├────────┼────────┼────────┼────────┼────────┼───────┤
Total │ 30 │ 28 │ 24 │ 25 │ 35 │ 36 │
───────────────┴────────┴────────┴────────┴────────┴────────┴───────┘
It will be noticed that when a marked excess of flowers of one kind
occurs one morning, a somewhat proportionate excess of the other type
occurs the following morning. This is of course necessary if an equal
number of the two types of flowers are to be produced and, to a certain
extent, to be maintained on the same plant; and is to be expected from
the alternate occurrence of the two types on opposite sides of the
raceme.
The flowers open early in the morning and remain open from three to
four days, depending somewhat upon the condition of the weather. Some
which were covered with cheese-cloth “tents” were noticed to remain
open almost a week. At the end of this period the corolla wilts and
falls off, as does also the pistil. The flowers seem to partially close
at night.
A limited series of experiments were made to determine if
self-fertilization and cross-fertilization between flowers of the
opposite type opening simultaneously on the same raceme are possible.[I]
The writers have not made sufficiently extensive observations to arrive
at any general conclusions of value as to the comparative fertility
of cross-and self-pollination, either between flowers on the same or
different racemes, or between the flowers of different plants, but they
have been able to obtain a limited series of definite results which may
be of interest.
In making experiments to determine these points, all old flowers were
removed from the plants in the afternoon or evening and the plants
covered with a small “tent” of cheese-cloth. The cheese-cloth was
of a mesh sufficiently small to prevent the access of any insects
large enough to effect pollination, while large enough to allow a
ready circulation of air and good illumination. The following morning
pollination was effected between the flowers which had opened by
tapping pollen from the large anther onto a clean glass slip and
transferring it to the stigma of the same or another flower. The
plant was then again covered and allowed to remain so, except when
examined from time to time, until the corolla and pistil had fallen
off. The following results were obtained from three plants upon which
observations were made: