Scientific American Supplement, Vol. XXI., No. 531, March 6, 1886 by Various
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Various >> Scientific American Supplement, Vol. XXI., No. 531, March 6, 1886
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To enter into consideration of the details of these constructions would
involve more time than is permitted us on this occasion. They are very
interesting. We come again naturally to the limitless consideration of
powdered fuel, concerning which certain conclusions have been reached.
In the dissociation of water into its hydrogen and oxygen, with the
mingled carbon in a powdered state, we undoubtedly possess the elements
of combustion that are unexcelled on earth, a heat-producing combination
that in both activity and power leaves little to be desired this side of
the production of the electric force and heat directly from the carbon
without the intermediary of boilers, engines, dynamos, and furnaces.
In the hope of stimulating thought to this infinite question of proper
fuel combustion, with its attendant possibilities for man's
gratification and ambition, this advanced step is presented. The
discussion of processes will require an amount of time which I hope this
Board will not grudgingly devote to the subject, but which is impossible
at present. Do not forget that there is no single spot on the face of
the globe where nature has lavished more freely her choicest gifts. Let
us be active in the pursuit of the treasure and grateful for the
distinguished consideration.
* * * * *
THE ORIGIN OF METEORITES.
On January 9, Professor Dewar delivered the sixth and last of his series
of lectures at the Royal Institution on "The Story of a Meteorite." [For
the preceding lectures, see SUPPLEMENTS 529 and 580.] He said that
cosmic dust is found on Arctic snows and upon the bottom of the ocean;
all over the world, in fact, at some time or other, there has been a
large deposit of this meteoric dust, containing little round nodules
found also in meteorites. In Greenland some time ago numbers of what
were supposed to be meteoric stones were found; they contained iron, and
this iron, on being analyzed at Copenhagen, was found to be rich in
nickel. The Esquimaux once made knives from iron containing nickel; and
as any such alloy they must have found and not manufactured, it was
supposed to be of meteoric origin. Some young physicists visited the
basaltic coast in Greenland from which some of the supposed meteoric
stones had been brought, and in the middle of the rock large nodules
were found composed of iron and nickel; it, therefore, became evident
that the earth might produce masses not unlike such as come to us as
meteorites. The lecturer here exhibited a section of the Greenland rock
containing the iron, and nickel alloy, mixed with stony crystals, and
its resemblance to a section of a meteorite was obvious. It was 21/2 times
denser than water, yet the whole earth is 51/2 times denser than water, so
that if we could go deep enough, it is not improbable that our own globe
might be found to contain something like meteoric iron. He then called
attention to the following tables:
_Elementary Substances found in Meteorites_.
Hydrogen. Chromium. Arsenic.
Lithium. Manganese. Vanadium?
Sodium. Iron. Phosphorus.
Potassium. Nickel. Sulphur.
Magnesium. Cobalt. Oxygen.
Calcium. Copper. Silicon.
Aluminum. Tin. Carbon.
Titanium. Antimony. Chlorine.
_Density of Meteorites_.
Carbonaceous (Orgueil, etc.) 1.9 to 3
Aluminous (Java) 3.0 " 3.2
Peridotes (Chassigny, etc.) 3.5 " --
Ordinary type (Saint Mes) 3.1 " 3.8
Rich in iron (Sierra de Chuco) 6.5 " 7.0
Iron with stone (Krasnoyarsk) 7.1 " 7.8
True irons (Caille) 7.0 " 8.0
_Interior of the Earth_
Parts
of the
radius. Density.
0.0 11.0
0.1 10.3
0.2 9.6
0.3 8.9
0.4 8.3
0.5 7.8
0.6 7.4
0.7 7.1
0.8 6.2
0.9 5.0
1.0 2.6
[Illustration]
Twice a year, said Professor Dewar, what are called "falling stars"
maybe plentifully seen; the times of their appearance are in August and
November. Although thousands upon thousands of such small meteors have
passed through our atmosphere, there is no distinct record of one having
ever fallen to the earth during these annual displays. One was said to
have fallen recently at Naples, but on investigation it turned out to be
a myth. These annual meteors in the upper air are supposed to be only
small ones, and to be dissipated into dust and vapor at the time of
their sudden heating; so numerous are they that 40,000 have been counted
in one evening, and an exceptionally great display comes about once in
331/4 years. The inference from their periodicity is, that they are small
bodies moving round the sun in orbits of their own, and that whenever
the earth crosses their orbits, thereby getting into their path, a
splendid display of meteors results. A second display, a year later,
usually follows the exceptionally great display just mentioned,
consequently the train of meteors is of great length. Some of these
meteors just enter the atmosphere of the earth, then pass out again
forever, with their direction of motion altered by the influence of the
attraction of the earth. He here called attention to the accompanying
diagram of the orbits of meteors.
The lecturer next invited attention to a hollow globe of linen or some
light material; it was about 2 ft. or 2 ft. 6 in. in diameter, and
contained hidden within it the great electro-magnet, weighing 2 cwt., so
often used by Faraday in his experiments. He also exhibited a ball made
partly of thin iron; the globe represented the earth, for the purposes
of the experiment, and the ball a meteorite of somewhat large relative
size. The ball was then discharged at the globe from a little catapult;
sometimes the globe attracted the ball to its surface, and held it
there, sometimes it missed it, but altered its curve of motion through
the air. So was it, said the lecturer, with meteorites when they neared
the earth. Photographs from drawings, by Professor A. Herschel, of the
paths of meteors as seen by night were projected on the screen; they all
seemed to emanate from one radiant point, which, said the lecturer, is a
proof that their motions are parallel to each other; the parallel lines
seem to draw to a point at the greatest distance, for the same reason
that the rails of a straight line of railway seem to come from a distant
central point. The most interesting thing about the path of a company of
meteors is, that a comet is known to move in the same orbit; the comet
heads the procession, the meteors follow, and they are therefore, in all
probability, parts of comets, although everything about these difficult
matters cannot as yet be entirely explained; enough, however, is known
to give foundation for the assumption that meteorites and comets are not
very dissimilar.
The light of a meteorite is not seen until it enters the atmosphere of
the earth, but falling meteorites can be vaporized by electricity, and
the light emitted by their constituents be then examined with the
spectroscope. The light of comets can be directly examined, and it
reveals the presence in those bodies of sodium, carbon, and a few other
well-known substances. He would put a piece of meteorite in the electric
arc to see what light it would give; he had never tried the experiment
before. The lights of the theater were then turned down, and the
discourse was continued in darkness; among the most prominent lines
visible in the spectrum of the meteorite, Professor Dewar specified
magnesium, sodium, and lithium. "Where do meteorites come from?" said
the lecturer. It might be, he continued, that they were portions of
exploded planets, or had been ejected from planets. In this relation, he
should like to explain the modern idea of the possible method of
construction of our own earth. He then set forth the nebular hypothesis
that at some long past time our sun and all his planets existed but as a
volume of gas, which in contracting and cooling formed a hot volume of
rotating liquid, and that as this further contracted and cooled, the
planets, and moons, and planetary rings fell off from it and gradually
solidified, the sun being left as the solitary comparatively uncooled
portion of the original nebula. In partial illustration of this, he
caused a little globe of oil, suspended in an aqueous liquid of nearly
its own specific gravity, to rotate, and as it rotated it was seen, by
means of its magnified image upon the screen, to throw off from its
outer circumference rings and little globes.
* * * * *
CANDELABRA CACTUS AND CALIFORNIA WOODPECKER.
By C.F. HOLDER.
One of the most picturesque objects that meet the eye of the traveler
over the great plains of the southern portion of California and New
Mexico is the candelabra cactus. Systematically it belongs to the Cereus
family, in which the notable Night-blooming Cereus also is naturally
included. In tropical or semi-tropical countries these plants thrive,
and grow to enormous size. For example, the Cereus that bears those
great flowers, and blooms at night, exhaling powerful perfume, as we see
them in hothouses in our cold climate, are even in the semi-tropical
region of Key West, on the Florida Reef, seen to grow enormously in
length.
[Illustration: THE CANDELABRA CACTUS--CEREUS GIGANTEUS.]
We cultivated several species of the more interesting forms during a
residence on the reef. Our brick house, two stories in height, was
entirely covered on a broad gable end, the branches more than gaining
the top. There is a regular monthly growth, and this is indicated by a
joint between each two lengths. Should the stalk be allowed to grow
without support, it will continue growing without division, and exhibit
stalks five or six feet in length, when they droop, and fall upon the
ground.
Where there is a convenient resting place on which it can spread out and
attach itself, the stalk throws out feelers and rootlets, which fasten
securely to the wall or brickwork; then, this being a normal growth,
there is a separation at intervals of about a foot. That is, the stalk
grows in one month about twelve inches, and if it has support, the
middle woody stalk continues to grow about an inch further, but has no
green, succulent portion, in fact, looks like a stem; then the other
monthly growth takes place, and ends with a stem, and so on
indefinitely. Our house was entirely covered by the stems of such a
plant, and the flowers were gorgeous in the extreme. The perfume,
however, was so potent that it became a nuisance. Such is the
Night-blooming Cereus in the warm climates, and similarly the Candelabra
Cereus grows in stalks, but architecturally erect, fluted like columns.
The flowers are large, and resemble those of the night-blooming variety.
Some columns remain single, and are amazingly artificial appearing;
others throw off shoots, as seen in the picture. There are some smaller
varieties that have even more of a candelabra look, there being clusters
of side shoots, the latter putting out from the trunk regularly, and
standing up parallel to each other. The enormous size these attain is
well shown in the picture.
Whenever the great stalks of these cacti die, the succulent portion is
dried, and nothing is left but the woody fiber. They are hollow in
places, and easily penetrated. A species of woodpecker, _Melanerpes
formicivorus_, is found to have adopted the use of these dry stalks for
storing the winter's stock of provisions. There are several round
apertures seen on the stems in the pictures, which were pecked by this
bird. This species of woodpecker is about the size of our common robin
or migratory thrush, and has a bill stout and sharp. The holes are
pecked for the purpose of storing away acorns or other nuts; they are
just large enough to admit the fruit, while the cup or larger end
remains outside. The nuts are forced in, so that it requires
considerable wrenching to dislodge them. In many instances the nuts are
so numerous, the stalk has the appearance of being studded with bullets.
This appearance is more pronounced in cases where the dead trunk of an
oak is used. There are some specimens of the latter now owned by the
American Museum of Natural History, which were originally sent to the
Centennial Exhibition at Philadelphia. They were placed in the
department contributed by the Pacific Railroad Company, and at that time
were regarded as some of the wonders of that newly explored region
through which the railroad was then penetrating. Some portions of the
surface of these logs are nearly entirely occupied by the holes with
acorns in them. The acorns are driven in very tightly in these examples;
much more so than in the cactus plants, as the oak is nearly round, and
the holes were pecked in solid though dead wood. One of the most
remarkable circumstances connected with this habit of the woodpecker is
the length of flight required and accomplished. At Mount Pizarro, where
such storehouses are found, the nearest oak trees are in the
Cordilleras, thirty miles distant; thus the birds are obliged to make a
journey of sixty miles to accomplish the storing of one acorn. At first
it seemed strange that a bird should spend so much labor to place those
bits of food, and so far away. De Saussure, a Swiss naturalist,
published in the _Bibliotheque Universelle_, of Geneva, entertaining
accounts of the Mexican Colaptes, a variety of the familiar "high hold,"
or golden winged woodpecker. They were seen to store acorns in the dead
stalks of the maguey (_Agave Americana_). Sumichrast, who accompanied
him to Central America, records the same facts. These travelers saw
great numbers of the woodpeckers in a region on the slope of a range of
volcanic mountains. There was little else of vegetation than the
_Agave_, whose barren, dead stems were studded with acorns placed there
by the woodpeckers.
The maguey throws up a stalk about fifteen feet in height yearly, which,
after flowering, grows stalky and brittle, and remains an unsightly
thing. The interior is pithy, but after the death of the stalk the pith
contracts, and leaves the greater portion of the interior hollow, as we
have seen in the case of the cactus branches. How the birds found that
these stalks were hollow is a problem not yet solved, but, nevertheless,
they take the trouble to peck away at the hard bark, and once
penetrated, they commence to fill the interior; when one space is full,
the bird pecks a little higher up, and so continues.
Dr. Heerman, of California, describes the California _Melanerpes_ as one
of the most abundant of the woodpeckers; and remarks that it catches
insects on the wing like a flycatcher. It is well determined that it
also eats the acorns that it takes so much pains to transport.
[Illustration: FLOWER OF CEREUS GIGANTEUS.]
It seems that these birds also store the pine trees, as well as the
oaks. It is not quite apparent why these birds exhibit such variation in
habits; they at times select the more solid trees, where the storing
cannot go on without each nut is separately set in a hole of its own.
There seems an instinct prompting them to do this work, though there may
not be any of the nuts touched again by the birds. Curiously enough,
there are many instances of the birds placing pebbles instead of nuts in
holes they have purposely pecked for them. Serious trouble has been
experienced by these pebbles suddenly coming in contact with the saw of
the mill through which the tree is running. The stone having been placed
in a living tree, as is often the case, its exterior had been lost to
sight during growth.
Some doubt has been entertained about the purpose of the bird in storing
the nuts in this manner. De Saussure tells us he has witnessed the birds
eating the acorns after they had been placed in holes in trees, and
expresses his conviction that the insignificant grub which is only seen
in a small proportion of nuts is not the food they are in search of.
C.W. Plass, Esq., of Napa City, California, had an interesting example
of the habits of the California _Melanerpes_ displayed in his own house.
The birds had deposited numbers of acorns in the gable end. A
considerable number of shells were found dropped underneath the eaves,
while some were found in place under the gable, and these were perfect,
having no grubs in them.
The picture shows a very common scene in New Mexico. The columns,
straight and angular, are often sixty feet in height. It is called torch
cactus in some places. There are many varieties, and as many different
shapes. Some lie on the ground; others, attached to trunks of trees as
parasites, hang from branches like great serpents; but none is so
majestic as the species called systematically _Cereus giganteus_, most
appropriately. The species growing pretty abundantly on the island of
Key West is called candle cactus. It reaches some ten or twelve feet,
and is about three inches in diameter. The angles are not so prominent,
which gives the cylinders a roundish appearance. They form a pretty,
rather picturesque feature in the otherwise barren undergrowth of
shrubbery and small trees. Accompanied by a few flowering cocoa palms,
the view is not unpleasing. The fiber of these plants is utilized in
some coarse manufactures. The maguey, or Agave, is used in the
manufacture of fine roping. Manila hemp is made from a species. The
species whose dried stalks are used by the woodpeckers for their winter
storage was cultivated at Key West, Florida, during several years before
1858. Extensive fields of the Agave stood unappropriated at that period.
Considerable funds were dissipated on this venture. Extensive works were
established, and much confidence was entertained that the scheme would
prove a paying one, but the "hemp" rope which this was intended to rival
could be made cheaper than this. The great Agave plants, with their long
stalks, stand now, increasing every year, until a portion of the island
is overrun with them.
CEREUS GIGANTEUS.
This wonderful cactus, its colossal proportions, and weird, yet grand,
appearance in the rocky regions of Mexico and California, where it is
found in abundance, have been made known to us only through books of
travel, no large plants of it having as yet appeared in cultivation in
this country. It is questionable if ever the natural desire to see such
a vegetable curiosity represented by a large specimen in gardens like
Kew can be realized, owing to the difficulty of importing large stems in
a living condition; and even if successfully brought here, they survive
only a very short time. To grow young plants to a large size seems
equally beyond our power, as plants 6 inches high and carefully managed
are quite ten years old. When young, the stem is globose, afterward
becoming club-shaped or cylindrical. It flowers at the height of 12
feet, but grows up to four or five times that height, when it develops
lateral branches, which curve upward and present the appearance of an
immense candelabrum, the base of the stem being as thick as a man's
body. The flower, of which a figure is given here, is about 5 inches
long and wide, the petals cream colored, the sepals greenish white.
Large clusters of flowers are developed together near the top of the
stem. A richly colored edible fruit like a large fig succeeds each
flower, and this is gathered by the natives and used as food under the
name of saguarro. A specimen of this cactus 3 feet high may be seen in
the succulent house at Kew.--_B., The Garden_.
* * * * *
HOW PLANTS ARE REPRODUCED.
[Footnote: Read at a meeting of the Chemists' Assistants' Association.
December 16, 1885.]
By C.E. STUART, B.Sc.
In two previous papers read before this Association I have tried to
condense into as small a space as I could the processes of the nutrition
and of the growth of plants; in the present paper I want to set before
you the broad lines of the methods by which plants are reproduced.
Although in the great trees of the conifers and the dicotyledons we have
apparently provision for growth for any number of years, or even
centuries, yet accident or decay, or one of the many ills that plants
are heirs to, will sooner or later put an end to the life of every
individual plant.
Hence the most important act of a plant--not for itself perhaps, but for
its race--is the act by which it, as we say, "reproduces itself," that
is, the act which results in the giving of life to a second individual
of the same form, structure, and nature as the original plant.
The methods by which it is secured that the second generation of the
plant shall be as well or even better fitted for the struggle of life
than the parent generation are so numerous and complicated that I cannot
in this paper do more than allude to them; they are most completely seen
in cross fertilization, and the adaptation of plant structures to that
end.
What I want to point out at present are the principles and not so much
the details of reproduction, and I wish you to notice, as I proceed,
what is true not only of reproduction in plants but also of all
processes in nature, namely, the paucity of typical methods of attaining
the given end, and the multiplicity of special variation from those
typical methods. When we see the wonderfully varied forms of plant life,
and yet learn that, so to speak, each edifice is built with the same
kind of brick, called a cell, modified in form and function; when we see
the smallest and simplest equally with the largest and most complicated
plant increasing in size subject to the laws of growth by
intussusception and cell division, which are universal in the organic
world; we should not be surprised if all the methods by which plants are
reproduced can be reduced to a very small number of types.
The first great generalization is into--
1. The vegetative type of reproduction, in which one or more ordinary
cells separate from the parent plant and become an independent plant;
and--
2. The special-cell type of reproduction, in which either one special
cell reproduces the plant, or two special cells by their union form the
origin of the new plant; these two modifications of the process are
known respectively as asexual and sexual.
The third modification is a combination of the two others, namely, the
asexual special cell does not directly reproduce its parent form, but
gives rise to a structure in which sexual special cells are developed,
from whose coalescence springs again the likeness of the original plant.
This is termed alternation of generations.
The sexual special cell is termed the _spore_.
The sexual special cells are of one kind or of two kinds.
Those which are of one kind may be termed, from their habit of yoking
themselves together, _zygoblasts_, or conjugating cells.
Those which are of two kinds are, first, a generally aggressive and
motile fertilizing or so-called "male cell," called in its typical form
an _antherozoid_; and, second, a passive and motionless receptive or
so-called "female cell," called an _oosphere_.
The product of the union of two zygoblasts is termed a _zygospore_.
The product of the union of an antherozoid and an oosphere is termed an
_oospore_.
In many cases the differentiation of the sexual cells does not proceed
so far as the formation of antherozoids or of distinct oospheres; these
cases I shall investigate with the others in detail presently.
First, then, I will point out some of the modes of vegetative
reproduction.
The commonest of these is cell division, as seen in unicellular plants,
such as protococcus, where the one cell which composes the plant simply
divides into two, and each newly formed cell is then a complete plant.
The particular kind of cell division termed "budding" here deserves
mention. It is well seen in the yeast-plant, where the cell bulges at
one side, and this bulge becomes larger until it is nipped off from the
parent by contraction at the point of junction, and is then an
independent plant.
Next, there is the process by which one plant becomes two by the dying
off of some connecting portion between two growing parts.
Take, for instance, the case of the liverworts. In these there is a
thallus which starts from a central point and continually divides in a
forked or dichotomous manner. Now, if the central portion dies away, it
is obvious that there will be as many plants as there were forkings, and
the further the dying of the old end proceeds, the more young plants
will there be.
Take again, among higher plants, the cases of suckers, runners, stolons,
offsets, etc. Here, by a process of growth but little removed from the
normal, portions of stems develop adventitious roots, and by the dying
away of the connecting links may become independent plants.
Still another vegetative method of reproduction is that by bulbils or
gemmae.
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