Where Do Sponges Come From?
Until within comparatively recent years, the sponge was regarded as
a plant; it is now known to belong to the animal kingdom, and to the
order spongida of the class of rhizopoda. Sponge is an elastic, porous
substance, formed of interlaced horny fibers, which produce by their
numerous inosculations, a rude sort of network, with meshes or pores
of unequal sizes, and usually of a square or angulated shape. Besides
these pores there are some circular holes of large size scattered
over the surface of most sponges, which lead into sinuous canals that
permeate their interior in every direction. The oscula, canals, and
pores, communicate freely together. The characteristic property of the
sponge is the facility with which it absorbs a large quantity of any
fluid, more especially of water, which is retained amid the meshes
until forced out again by a sufficient degree of compression, when the
sponge returns to its former bulk. From this peculiarity, combined with
its pleasant softness, arises the value of the sponge for the purposes
to which it is applied. In domestic economy and in surgical practice,
there is no other product that can be satisfactorily substituted for it.
Sponge is an aquatic production, indigenous to almost every sea and
shore. It is abundant and varied between the tropics, but becomes
less so in temperate latitudes and continues to diminish in quantity,
variety, and size, as it is traced into European and colder seas, until
it almost disappears in the vicinity of the polar circles. Some sponges
are known to be hermaphrodite, but that the individual at one period
produces chiefly male elements, and later, chiefly female elements.
Fertilization takes place in the body of the mother, and the egg here
undergoes its early development. The embryo eventually bursts the
maternal tissue and, passing into one of the canals, is caught by the
current sweeping through the canal system and is discharged into the
surrounding water through one of the large apertures on the surface
of the sponge. In the Bahama Islands and along the coast of Florida,
the breeding time of many sponges covers the period from mid-summer on
through early Autumn.
There is propagation sometimes by ciliated gemmules, yellowish and
oval, arising from the sarcode mass, and carried out by the currents.
These are mostly formed in the spring, and after swimming freely about
for a time, become fixed and grow. In its natural state, the sponge
is a very different looking object from the article of commerce. The
entire surface is covered with a thin, slimy skin, usually of a dark
color, and perforated to correspond with the apertures of the canals.
The sponge of commerce is in reality only the home or the skeleton of
the sponge.
There are a few sponges that inhabit ponds and sluggish rivers; the
others are marine. Of these, many of the calcareous and siliceous kinds
inhabit the shores between tide-marks, preferring a site near the low
ebb, where, nevertheless, they are daily alternately submerged, and
left exposed to the atmosphere. The figured sponges with a fibrous
texture, to whatever genus they belong, are denizens of deeper water,
and are never left uncovered. They grow usually in groups, on rock
shells, shellfish, corallines, and seaweeds, and either have no power
of selection, or the quality of the site is indifferent to them.
How Do Sponges Grow?
In their growth, some sponges assume a determinate figure or at least
one whose variations are confined within certain limits. The greater
number are irregular and variable, their shape depending in a great
measure upon the peculiarities of their state, to which they easily
accommodate themselves. They will incrust a shell, or a crab, a rock,
or seaweed, following every projection and sinuosity. The offshoots
will spring up with a more luxuriant growth in the deeper sheltered
places until the original shape of the foundation they grow upon is
lost to sight.
Sponges are unmoving and inirritable. They never remain rooted to the
places of the germination, and are incapable either of contracting or
dilating themselves or even of moving any fiber or portion of their
mass. The functions which distinguish them as living beings are few,
and faintly imaged.
How Do Sponges Eat?
Although sponges lack the power of motion possessed by most animals,
being nearly always attached, in one position or another, to some
object, the study of their habits in captivity brings out many of their
animal characteristics in a striking manner. Small specimens taken
from the sea and placed in dishes of salt water may be kept alive for
several hours if well cared for; and by using finely powdered coloring
matter, such as carmine or indigo, the manner of their feeding may be
readily observed. Sponges are more active in fresh sea water than in
stale; they cannot be kept alive out of water and soon die if exposed
to the air. Being unable to go in search of food, as a natural result,
they can grow only in places where there is always an abundance of
food suited to their wants. The great sponging grounds of the world
are wholly confined within waters having a relatively high temperature
during the entire year. The Old World sponges grow principally in
the Mediterranean and the Red seas; the New World sponges are found
about the Bahamas, southern and western Florida, and parts of the West
Indies. The finest sponges come from the East, but one of the American
species, the so-called “sheep’s wool,” stands high in favor.
The commercial sponges are separated into six species, three of which
are European and three American. They are all referred to a single
genus called spongia, and though having much in common as regards
structure, their texture varies to such an extent as to make them of
very unequal value for domestic purposes.
The Old World species may be arranged as follows, in order of their
grade of excellence, beginning with the best quality: The Turkey cup
sponge, Levant toilet sponge, the horse, honey comb, or bath sponge,
and the Zimoca sponge. The American species include the sheep’s wool
sponge, the yellow glove, violet, and grass, sponges. A very close
relationship exists between the species of the two continents.
All known regions in which useful specimens abound contribute to the
world’s supply. The trade is extensive. The demands upon the fisheries
are great. In the Mediterranean, the fishing is carried on in some
places at a depth of forty fathoms. Divers, naked, or in armor, go down
to the bottom and tear off the sponges from their places of growth. In
some places drag dredges are employed.
How Are Sponges Caught?
In the past quarter-century the sponge-fishery of the Florida coast has
grown remarkably. Its headquarters is at Key West and several hundred
sailing vessels are engaged in the industry. The fishing appliances
consist of a small boat, a long hook, and a waterglass. The hook is
in reality a three-pronged spear attached to a pole thirty-five feet
long. In searching for sponge the fishers row about in the small
boat. By holding the glass on the surface of the water the bottom is
plainly seen and small objects are readily discerned. When a sponge is
sighted the pole with the hook attached is shot down and the product
deftly gathered. The boat-load is brought to the deck of the schooner,
allowed to remain there a few hours, and then is carried down into the
hold. On Friday nights, the fishing generally ends for the week, and
the vessel sails for some spot on the neighboring coast where there
are established crawls, or places for curing the catch. These crawls
are about 8 x 10 feet square, their purpose being to hold the sponges
while maceration and decomposition take place. The resulting refuse is
carried off by the tide.
The fishermen go away for another catch and the sponges are left in the
crawls until the end of the following week when a new cargo is brought
in. The returning fishermen beat the decomposed sponges with clubs,
removing the impurities. The water is squeezed out, then the sponges
are allowed to dry on the ground.
After drying, the hold of the large vessel is loaded to the utmost
with the product and the voyage to Key West is made. Buyers from New
York look over the sponges, and make offers for entire cargoes. The
fishermen dispose of their goods rapidly and sail away for more. The
buyers store the sponges in some dry building, and cause them to be
bleached by lime. A popular manner of bleaching is to wash the sponges
thoroughly in water, and then to immerse them in diluted hydrochloric
acid to dissolve any of the calcareous substance. Having again been
washed they are placed in another bath of dilute hydrochloric acid to
which six per cent. of hyposulphite of soda, dissolved in a little warm
water, has been added. In this bath the sponges remain for twenty-four
hours, or until the bleaching process is completed. After bleaching,
the sponges are pressed until their bulk is greatly reduced; they are
then baled, and shipped to New York, which is the distributing point
for the entire Florida product.
Sponges are by far the most important fishery products of Florida,
representing about one-third of the annual value of the fishing
industry. In 1899, the yield was over 350,000 pounds of sponges of
which the first value was nearly $400,000.
Why Does Yeast Make Bread Rise?
There is a lot of sugar in the dough from which bread is made. Sugar
contains three things--carbon, hydrogen and oxygen. When sugar is
fermented it amounts practically to burning it. To make good bread
from the dough it is necessary to ferment the sugar which is in the
ingredients from which it is made. Yeast, which is a simple living
plant, has the power to ferment sugar. When sugar ferments, two things
are produced. One thing is the formation of carbonic acid gas. A great
deal of this carbonic acid gas is caught in the dough in the form of
large or small bubbles and some of it escapes into the air. The other
part tries to escape into the air also but cannot, and causes the dough
to rise, which makes the bread light, as we say. The holes you see in
the bread after it is baked are the little pockets where the carbonic
acid gas was retained in the dough. These bubbles of gas all through
the dough act like a lot of little balloons and lift the dough up with
themselves as they try to get to the top and escape into the air.
What Is Yeast?
Yeast is a living plant that is used for the purpose of causing
fermentation. The yeast we use in baking bread is an artificial
yeast--really a dough made of flour and a little common yeast and made
into small cakes and dried. If kept free from moisture it retains the
power of causing fermentation for some time. The flour and other matter
in a cake of yeast are only used to keep the yeast in a form where it
can be preserved. It is necessary to add water to start fermentation
and that is why we add hot water when we stir in the yeast for a baking.
Is a Moth Attracted By a Light?
It seems to be a strange contradiction of the nature of living things
that a moth should fly deliberately into a light or dash itself to
death against the glass surrounding a strong light. This is contrary
to the usual law of nature which gives the living thing an instinct to
protect itself against enemies.
For a long time we thought that moths did not deliberately burn
themselves up by flying right into a light, but our naturalists
have proven that not only moths but certain birds, bees, flies and
butterflies, burn themselves up by flying into the flame of a light or
fire.
[Illustration: HOW MAN LEARNED TO MAKE A FIRE