Vol. XXV. No. 11.] 
POPULAE SCIENCE KEWS. 
169 
orgiins of reproduction. ITiese organs are what 
is ordinarity termed the "flower," though it will 
he remembered that in the botanical sense flowers 
are also borne by the Gymnosperms. being charac- 
teristic of the great primarj' division Ph(enerogn- 
mia. The flower of the Anriiosperms is more 
highly developed than that of the lower class; 
it presents a larger number of sets of parts, and 
of tlie.se the essential ones are distinctly dift'ereut 
from those of the gymnospermous plants. 
Following our method, we may make special 
reference to a typical plant of the group, and for 
this purpose we select, as a plaut whose flower is 
familiarly known, the apple-tree. The reader is 
recommended to obtain for present examination 
and for comparison witli the description below 
the flower of any plant now in bloom, whether 
growing in the fleld or under in-door cultivation. 
The flower of the apple-tree, the beautiful and 
fragrant apple-blossom, looked upon from tlie 
point of view of structural botany, is made up of 
four sets, or whorls, of leaves. The lowermost 
whorl consists' of five green leaflets, called sepals, 
united below to a cup-.shaped part, the whole 
forming the calyx. The next circle of leaves is 
the five colored petals, forming the showj' part of 
the flower, and together constituting the corolla. 
Next are the dozen or more stamens, together 
making the andrcecium, inserted on the margin of 
the calyx. Finally, the uppermost whorl of 
parts, and nearest the middle of the flower, is the 
the yyncecmm, made up of five parts, each of 
which is a pistil. The lower part of each pistil is 
the ovary, and is adherent to the inside of the 
calyx. While the sepals resemble leaves closely 
enough, being green blades, and the petals are 
clearly leaves of white and pink color, instead of 
green, it does not appear at first sight that the 
other two circles of parts, the stamens and pis- 
tils, should be regarded as leaves. However, it is 
not to be doubted tliat they are simply modified 
leaves. Proof is aftbrded by studying the devel- 
opment of the flower, when it is found that each 
stamen and pistil begins as a tiny leaf-blade and 
grows into the greatly modified form seen in the 
flower. Further proof exists in the fact that in 
some flowers — the water-lily, for instance — there 
is a perfect gradation between the lowest green 
leaf-like sepals to the highest (inmost) pistils of 
characteristic shape. 
^Ve need give particular attention to the pistils 
of the flower. The ovary below is surmounted by 
a delicate stalk, the style, which expands at the 
top into tlie stigma. If an ovary is cut across and 
examined under magnification it will be seen to 
consist of a hollow case containing two very 
small bodies, the ovules. A further use of the 
microscope shows that each ovule contains within 
a minute sac, the emhryo sac, within which again 
is a simple cell, the embryonic vesicle. The em- 
l)ryonic vesicle is the essential part of the pistil. 
It is. the germ from which a new plaut may be 
derived. Its development follows upon fertiliza- 
tion by a pollen-grain, produced in the anther, or 
box-like upper portion of the stamen. The pollen- 
cell falls upon tlie stigma, sprouts, grows down 
the hollow style, penetrates the walls of the 
ovule and the embryo sac, and thus unites with 
the embryonic vesicle. This cell then develops 
into a tiny miniature plant, remaining within the 
walls of tlie ovule, the whole thus couslitutiug 
the seed. 
Let us now notice the features of the flower, 
considered as a reproductive organ, which are 
characteristic of the Angiosperms. They are, first 
and most important, the closed ovai'y. The ovules 
— the parts destined to become seeds — are en- 
closed in a protective case, technically called the 
carpel, representing, in fact, a leaf folded until its 
edges have met and grown together. Now in the 
Gymnosperms the ovules are also borne on carpels, 
but they have not become transformed into pro- 
tective cases. The leaf has only become con- 
verted into a thickened scale (of the cone) and 
bears tlie ovules exposed upon its inner face. 
The second difl'erence between the flower of the 
Angiosperms and that of the lower class is that 
the former possesses, besides the essential parts, 
which are the pistils and stamens, — identical in 
nature with those of the Gymnosperms, — subsidiary 
parts, the sepals and the petals. That these are 
in fact merely auxiliary structures is evident when 
it is considered that they have no part whatever in 
the production of the seed. Moreover, absolute 
proof of their secondary importance is afforded in 
the! fact that their parts are wanting altogether in 
some angiospermous plants. Of what use to the 
plant, then, are the sepals and petals? The for- 
mer are simply protective, especially when the 
flowei- is in the bud stage, when they enclose the 
other parts. The petals, at least in the case of 
very manj' plants, have a more important use. 
Their bright colors are adapted to attract insects, 
by the agency of which pollen is carried from the 
flowers of one plant to those of anotlier, thus 
eftectiug cross-fertilization and preventing the 
deterioration of the species. 
There is considerable difference between the 
two classes of flowering plants in respect to the 
minute structure of the wood. The Gymnosperms 
lack a definite vascular tissue. They possess no 
ducts for conveying the air and fluids through 
the plant-body, but are dependent for their circu- 
lation upon a process of dift'usion from cell to cell 
of the ordinary tissues. The physiological princi- 
ple is the same in the two groups, only in the An- 
giosperms one set of cells has become dilTerentiated 
into a special vascular tissue. In respect to the 
general arrangement of the woody tissues there is 
a substantial similarity between the Gymnosperms 
aud the exogenous Angiosperms — both having the 
ringed structure, each ring showing a year's 
growth. 
In the preceding paper of this series it was 
pointed out that as we pass from the highest flow- 
erless plants to the lowest flower-bearers there is 
no sudden change in structure and functions, but 
a gradual transition from one group to the other. 
In the present paper some suggestion is given of 
the continuance of this principle of gradual pro- 
gressive change from the lowest flowering plants 
up the scale of life to the highest members of the 
vegetable kingdom. 
Union College, SciiENECTAoy, N. Y. 
[Specially Observed for Popular Science News.] 
METEOKOLOGY FOR SEPTEMBER, 1891. 
TE.MPERATURE. 
Average Thermometer. 
Lowest. 
Highest. 
Bange. 
AtTA.M 
At2P. M 
AtHP. M 
Whole month .... 
Second average . . ■ 
60.53' 
71.67° 
62.63" 
64.»4' 
64.37° 
61.56° 
60.87° 
60' 
61° 
SO- 
SO' 
60° 
70° 
83° 
76° 
83° 
83° 
20° 
22° 
26° 
33° 
33° 
Last -21 Septembers . . 
Second average . . 
I S7.S6° 
j in 1887. 
,')6.68° 
66.69° ) 
in 1881. ! 
66.12° 
9.33° 
9.44° 
the 18th, which was also the warmest day, with 
an average of 75.33°. The 25th averaged 73°. 
The whole month was 3.38° above the average of 
the- last twenty-one Septembers, and was the 
warmest, with one exception — that of 1881.- The 
extremes are shown in the table. The noon ob- 
servations the last half of the month averaged 
4.53° warmer than the first half. No frost up to 
date. 
. SKY. 
The face of the sky, in 90 observations, gave 63 
fair, 6 cloudy, 17 overcast, and 4 rainy, — a per- 
centage of 70.0 fair. The average fair for the last 
twenty-one Septembers has been only 58.1, with 
extremes of .35.5 in 188-2, and 77.7 in 1877. The 
percentage fair has been exceeded but twice in 
September during this period. An unusual num- 
ber of days were noted "fine," and the mornings 
of the 22d and 27th were foggy. The beautiful, 
fine weather occasioned very frequent remark, 
and hastened the maturing of many fruits. 
PRECIPITATION. 
The amount of rainfall the last month was 2.60 
inches, all of which fell on the 7th, excTipt .10 inch 
on the 13th, leaving the rest of the month desti- 
tute — with a slight trace only on the 29th — and 
threatening drouth. 'The average precipitation 
the last twenty-three Septembers has been 3.02 
inches, with extremes of .45 inch in 1877, and 9.88 
in 1888. The amount since January 1 has been 
43.87 inches, and the average of these nine months 
35. ,38, — giving us an excess of 8.49 inches thus far 
the present year. 
PRESSURE. 
The average pressure the past month was 30.092 
inches, with extremes of 29.82 on the 14th, and 
30.32 on the 30th, — a range of .50 inch. The mean 
for the last eighteen Septembers has been 30.032 
inches, with extremes of 29.915 in 1876, and 30.110 
in 1887, — a range of .105 inch. The mean daily 
movement the last month was .118 inch, while this 
average tlie past eighteen Septembers has been 
.125 inch, with extremes of .074 and .164. The 
largest daily movement was .30 on the 18th. The 
barometer was stationary at one-fourth of the 
observations. 
■WINDS. 
The average direction of the wind the past 
month was VV. 19° 53' N., while the mean for the 
last twenty-two Septembers has been only W. 6° 
44' N., with extremes of W. 64° 30' S. in 1877, and 
E. 76° 0' N. in 1874,— a range of 168° 30', or about 
fifteen points of the compass. The winds the 
present month have been 13° 9' more northerly 
than usual, notwithstanding the high tempera- 
ture. The relative progressive distance travelled 
by the wind the past month was just 50 units, 
and during tlie last twenty-two Septembers 589 
such units, an average of 26.78, — showing much 
less easterly winds than usual. 
Thus far in the year we have received 440° of 
heat above the mean of the same months for the 
last twentj'-one years, equal to a daily mean of 
1.61°. This surplus from the sun, with an excess 
of 8.49 inciies of rain from the clouds, has resulted 
in rich harvests in the field and abundant — or 
rather superabundant — fruits in the orchard and 
garden. D. VV. 
Natick, Oct. 5, 1891. . 
This month has been remarkably warm, fair, 
and dry. The lowest point reached by the mer- 
cury w as 50°, on the morning of the 9th and even- 
ing of the .30th, which last was the coolest day, 
averaging 55.06°. The highest point was 83°, on 
[Specially Computed for Popular sciekcb News.] 
ASTRONOMICAL PHENOMENA FOR 
NOVEMBER, 1891. 
There will be two eclipses during the month. 
The first, an eclipse of the moon on November 15, 
will be visible throughout North and South Amer- 
