Atlantic Monthly, Vol. 10, No. 61, November, 1862 by Various

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It is not, however, my purpose here to describe the various modes of
reproduction and multiplication among animals and plants, nor to discuss
the merits of the different opinions respecting their numeric increase,
according to which some persons hold that all types originated from a
few primitive individuals, while others believe that the very numbers
now in existence are part of the primitive plan, and essential to the
harmonious relations existing between the animal and vegetable world. I
would only attempt to show that in the plan of Creation the maintenance
of types has been secured through a variety of means, but under such
limitations, that, within a narrow range of individual differences, all
representatives of one kind of animals agree with one another, whether
derived from eggs, or produced by natural division, or by budding; and
that the constancy of these normal processes of reproduction, as well as
the uniformity of their results, precludes the idea that the specific
differences among animals have been produced by the very means that
secure their permanence of type. The statement itself implies a
contradiction, for it tells us that the same influences prevent and
produce change in the condition of the Animal Kingdom. Facts are all
against it; there is not a fact known to science by which any single
being, in the natural process of reproduction and multiplication, has
diverged from the course natural to its kind, or in which a single kind
has been transformed into any other. But this once established, and
setting aside the idea that Embryology is to explain to us the origin as
well as the maintenance of life, it yet has most important lessons for
us, and the field it covers is constantly enlarging as the study
is pursued. The first and most important result of the science of
Embryology was one for which the scientific world was wholly unprepared.
Down to our own century, nothing could have been farther from the
conception of anatomists and physiologists than the fact now generally
admitted, that all animals, without exception, arise from eggs. Though
Linnaeus had already expressed this great truth in the sentence so often
quoted,--"Omne vivum ex ovo,"--yet he was not himself aware of the
significance of his own statement, for the existence of the Mammalian
egg was not then dreamed of. Since then the discoveries of von Baer and
others have shown not only that the egg is common to all living beings
without exception, from the lowest Radiate to the highest Vertebrate,
but that its structure is at first identical in all, composed of the
same primitive elements and undergoing exactly the same process of
growth up to the time when it assumes the special character peculiar
to its kind. This is unquestionably one of the most comprehensive
generalizations of modern times.

In common parlance, we understand by an egg something of the nature of a
hen's egg, a mass of yolk surrounded with white and inclosed in a shell.
But to the naturalist, the envelopes of the egg, which vary greatly in
different animals, are mere accessories, while the true egg, or, as it
is called, the ovarian egg, with which the life of every living being
begins, is a minute sphere, uniform in appearance throughout the Animal
Kingdom, though its intimate structure is hardly to be reached even with
the highest powers of the microscope. Some account of the earlier stages
of growth in the egg may not be uninteresting to my readers. I will
take the egg of the Turtle as an illustration, since that has been the
subject of my own especial study; but, as I do not intend to carry my
remarks beyond the period during which the history of all vertebrate
eggs is the same, they may be considered of more general application.

It is well known that all organic structures, whether animal or
vegetable, are composed of cells. These cells consist of an outside bag
inclosing an inner sac, and within that sac there is a dot. The outer
bag is filled with semi-transparent fluid, the inner one with a
perfectly transparent fluid, while the dot is dark and distinct. In the
language of our science, the outer envelope is called the Ectoblast, the
inner sac the Mesoblast, and the dot the Entoblast. Although they are
peculiarly modified to suit the different organs, these cells never lose
this peculiar structure; it may be traced even in the long drawn-out
cells of the flesh, which are like mere threads, but yet have their
outer and inner sac and their dot,--at least while forming.

In the Turtle the ovary is made up of such cells, spherical at first,
but becoming hexagonal under pressure, when they are more closely packed
together. Between these ovarian cells the egg originates, and is at
first a mere granule, so minute, that, when placed under a very high
magnifying power, it is but just visible. This is the incipient egg,
and at this stage it differs from the surrounding cells only in being
somewhat darker, like a drop of oil, and opaque, instead of transparent
and clear like the surrounding cells. Under the microscope it is found
to be composed of two substances only: namely, oil and albumen. It
increases gradually, and when it has reached a size at which it requires
to be magnified one thousand times in order to be distinctly visible,
the outside assumes the aspect of a membrane thicker than the interior
and forming a coating around it. This is owing not to an addition from
outside, but to a change in the consistency of the substance at the
surface, which becomes more closely united, more compact, than the
loose mass in the centre. Presently we perceive a bright, luminous,
transparent spot on the upper side of the egg, near the wall or outer
membrane. This is produced by a concentration of the albumen, which
now separates from the oil and collects at the upper side of the egg,
forming this light spot, called by naturalists the Purkinjean vesicle,
after its discoverer, Purkinje. When this albuminous spot becomes
somewhat larger, there arises a little dot in the centre,--the germinal
dot, as it is called. And now we have a perfect cell-structure,
differing from an ordinary cell only in having the inner sac, inclosing
the dot, on the side, instead of in the centre. The outer membrane
corresponds to the Ectoblast, or outer cell sac, the Purkinjean vesicle
to the Mesoblast, or inner cell sac, while the dot in the centre answers
to the Entoblast. When the Purkinjean vesicle has completed its growth,
it bursts and disappears; but the mass contained in it remains in the
same region, and retains the same character, though no longer inclosed
as before.

At a later stage of the investigation, we see why the Purkinjean
vesicle, or inner sac of the egg, is placed on the side, instead of
being at the centre, as in the cell. It arises on that side along which
the axis of the little Turtle is to lie,--the opposite side being that
corresponding to the lower part of the body. Thus the lighter, more
delicate part of the substance of the egg is collected where the upper
cavity of the animal, inclosing the nervous system and brain, is to
be, while the heavy oily part remains beneath, where the lower cavity,
inclosing all the organs of mere material animal existence, is
afterwards developed. In other words, when the egg is a mere mass of
oil and albumen, not indicating as yet in any way the character of the
future animal, and discernible only by the microscope, the distinction
is indicated between the brains and the senses, between the organs of
instinct and sensation and those of mere animal functions. At that stage
of its existence, however, when the egg consists of an outer sac, an
inner sac, and a dot, its resemblance to a cell is unmistakable; and,
in fact, an egg, when forming, is nothing but a single cell. This
comparison is important, because there are both animals and plants
which, during their whole existence, consist of a single organic cell,
while others are made up of countless millions of such cells. Between
these two extremes we have all degrees, from the innumerable cells that
build up the body of the highest Vertebrate to the single-celled Worm,
and from the myriad cells of the Oak to the single-celled Alga.

But while we recognize the identity of cell-structure and egg-structure
at this point in the history of the egg, we must not forget the great
distinction between them,--namely, that, while the cells remain
component parts of the whole body, the egg separates itself and assumes
a distinct individual existence. Even now, while still microscopically
small, its individuality begins; other substances collect around it, are
absorbed into it, nourish it, serve it. Every being is a centre about
which many other things cluster and converge, and which has the power to
assimilate to itself the necessary elements of its life. Every egg is
already such a centre, differing from the cells that surround it by
no material elements, but by the principle of life in which its
individuality consists, which is to make it a new being, instead of a
fellow-cell with those that build up the body of the parent animal and
remain component parts of it. This intangible something is the subtile
element that eludes our closest analysis; it is the germ of the
immaterial principle according to which the new being is to develop. The
physical germ we see; the spiritual germ we cannot see, though we may
trace its action on the material elements through which it is expressed.

The first change in the yolk, after the formation of the Purkinjean
vesicle, is the appearance of minute dots near the wall at the side
opposite the vesicle. These increase in number and size, but remain
always on that half of the yolk, leaving the other half of the globe
clear. One can hardly conceive the beauty of the egg as seen through the
microscope at this period of its growth, when the whole yolk is divided,
with the dark granules on one side, while the other side, where the
transparent halo of the vesicle is seen, is brilliant with light. With
the growth of the egg these granules enlarge, become more distinct, and
under the microscope some of them appear to be hollow. They are not
round in form, but rather irregular, and under the effect of light they
are exceedingly brilliant. Presently, instead of being scattered equally
over the space they occupy, they form clusters,--constellations, as it
were,--and between these clusters are clear spaces, produced by the
separation of the albumen from the oil.

At this period of its growth there is a wonderful resemblance between
the appearance of the egg, as seen under the microscope, and
the firmament with the celestial bodies. The little clusters or
constellations are unequally divided: here and there they are two and
two like double stars, or sometimes in threes or fives, or in sevens,
recalling the Pleiades, and the clear albuminous tracks between are like
the empty spaces separating the stars.

This is no fanciful simile: it is simply true that such is the actual
appearance of the yolk at this time; and the idea cannot but suggest
itself to the mind, that the thoughts which have been at work in the
universe are collected and repeated here within this little egg, which
offers us a miniature diagram of the firmament. This is one of the first
changes of the yolk, ending by forming regular clusters with a sort
of net-work of albumen between, and then this phase of the growth is
complete.

Now the clusters of the yolk separate, and next the albumen in its turn
concentrates into clusters, and the dark bodies, which have been till
now the striking points, give way to the lighter spheres of albumen
between which the clusters are scattered. Presently the whole becomes
redissolved: these stages of the growth being completed, this little
system of worlds is melted, as it were: but while it undergoes this
process, the albuminous spheres, after being dissolved, arrange
themselves in concentric rings, alternating with rings of granules,
around the Purkinjean vesicle. At this time we are again reminded of
Saturn and its rings, which seems to have its counterpart here. These
rings disappear, and now once more out of the yolk mass loom up little
dots as minute as before; but they are round instead of angular, and
those nearest the Purkinjean vesicle are smaller and clearer, containing
less of oil than the larger and darker ones on the opposite side. From
this time the yolk begins to take its color, the oily cells assuming a
yellow tint, while the albuminous cells near the vesicle become whiter.

Up to this period the processes in the different cells seem to have been
controlled by the different character of the substance of each; but now
it would seem that the changes become more independent of physical or
material influences, for each kind of cell undergoes the same process.
They all assume the ordinary cell character, with outer and inner
sac,--the inner sac forming on the side, like the Purkinjean vesicle
itself; but it does not retain this position, for, as soon as its wall
is formed and it becomes a distinct body, it floats away from the side
and takes its place in the centre. Next there arise within it a number
of little bodies crystalline in form, and which actually are wax or oil
crystals. They increase with great rapidity, the inner sac or mesoblast
becoming sometimes so crowded with them, that its shape is affected by
the protrusion of their angles. This process goes on till all the cells
are so filled by the mesoblast, with its myriad brood of cells, that
the outer sac or ectoblast becomes a mere halo around it. Then every
mesoblast contracts; the contraction deepens, till it is divided across
in both directions, separating thus into four parts, then into eight,
then into sixteen, and so on, till every cell is crowded with hundreds
of minute mesoblasts, each containing the indication of a central dot or
entoblast. At this period every yolk cell is itself like a whole yolk;
for each cell is as full of lesser cells as the yolk-bag itself.

When the mesoblast has become thus infinitely subdivided into hundreds
of minute spheres, the ectoblast bursts, and the new generations of
cells thus set free collect in that part of the egg where the embryonic
disk is to arise. This process of segmentation continues to go on
downward till the whole yolk is taken in. These myriad cells are in
fact the component parts of the little Turtle that is to be. They will
undergo certain modifications, to become flesh-cells, blood-cells,
brain-cells, and so on, adapting themselves to the different organs they
are to build up; but they have as much their definite and appointed
share in the formation of the body now as at any later stage of its
existence.

We are so accustomed to see life maintained through a variety of
complicated organs that we are apt to think this the only way in which
it can be manifested; and considering how closely life and the organs
through which it is expressed are united, it is natural that we should
believe them inseparably connected. But embryological investigations
have shown us that in the commencement none of these organs are formed,
and yet that the principle of life is active, and that even after they
exist, they cannot act, inclosed as they are. In the little Chicken, for
instance, before it is hatched, the lungs cannot breathe, for they
are surrounded by fluid, the senses are inactive, for they receive no
impressions from without, and all those functions establishing its
relations with the external world lie dormant, for as yet they are not
needed. But they are there, though, as we have seen in the Turtle's egg,
they were not there at the beginning. How, then, are they formed? We may
answer, that the first function of every organ is to make itself. The
building material is, as it were, provided by the process which divides
the yolk into innumerable cells, and by the gradual assimilation and
modification of this material the organs arise. Before the lungs
breathe, they make themselves; before the stomach digests, it makes
itself; before the organs of the senses act, they make themselves;
before the brain thinks, it makes itself; in a word, before the whole
system works, it makes itself; its first office is self-structure.

At the period described above, however, when the new generations of
cells are just set free and have taken their place in the region where
the new being is to develop, nothing is to be seen of the animal whose
life is beginning there, except the filmy disk lying on the surface of
the yolk. Next come the layers of white or albumen around the egg, and
last the shell which is formed from the lime in the albumen. There is
always more or less of lime in albumen, and the hardening of the last
layer of white into shell is owing only to the greater proportion of
lime in its substance. In the layer next to the shell there is enough of
lime to consolidate it slightly, and it forms a membrane; but the white,
the membrane, and the shell have all the same quality, except that the
proportion of lime is more or less in the different layers.

But, as I have said, the various envelopes of eggs, the presence or
absence of a shell, and the absolute size of the egg, are accessory
features, belonging not to the egg as egg, but to the special kind of
being from which the egg has arisen and into which it is to develop.
What is common to all eggs and essential to them all is that which
corresponds to the yolk in the bird's egg. But their later mode of
development, the degree of perfection acquired by the egg and germ
before being laid, the term required for the germ to come to maturity,
as well as the frequency and regularity of the broods, are all features
varying with the different kinds of animals. There are those that lay
eggs once a year at a particular season and then die; so that their
existence may be compared to that of annual plants, undergoing their
natural growth in a season, to exist during the remainder of the year
only in the form of an egg or seed. The majority of Insects belong to
this category, as do also our large Jelly-Fishes; many others have a
slow growth, extending over several years, during which they reach their
maturity, and for a longer or shorter time produce broods at fixed
intervals; while others, again, reach their mature state very rapidly,
and produce a number of successive generations in a comparatively short
time, it may be in a single season.

I do not intend to enter upon the chapter of special differences of
development among animals, for in this article I have aimed only to show
that the egg lives, that it is itself the young animal, and that
the vital principle is active in it from the earliest period of its
existence. But I would say to all young students of Embryology that
their next aim should be to study those intermediate phases in the life
of a young animal, when, having already acquired independent existence,
it has not yet reached the condition of the adult. Here lies an
inexhaustible mine of valuable information unappropriated, from which,
as my limited experience has already taught me, may be gathered the
evidence for the solution of the most perplexing problems of our
science. Here we shall find the true tests by which to determine the
various kinds and different degrees of affinity which animals now living
bear not only to one another, but also to those that have preceded them
in past times. Here we shall find, not a material connection by which
blind laws of matter have evolved the whole creation out of a single
germ, but the clue to that intellectual conception which spans the whole
series of the geological ages and is perfectly consistent in all its
parts. In this sense the present will indeed explain the past, and the
young naturalist is happy who enters upon his life of investigation now,
when the problems that were dark to all his predecessors have received
new light from the sciences of Palaeontology and Embryology.

* * * * *

BLIND TOM.

Only a germ in a withered flower,
That the rain will bring out--sometime.

Sometime in the year 1850, a tobacco-planter in Southern Georgia
(Perry H. Oliver by name) bought a likely negro woman with some other
field-hands. She was stout, tough-muscled, willing, promised to be a
remunerative servant; her baby, however, a boy a few months old, was
only thrown in as a makeweight to the bargain, or rather because Mr.
Oliver would not consent to separate mother and child. Charity only
could have induced him to take the picaninny, in fact, for he was but
a lump of black flesh, born blind, and with the vacant grin of idiocy,
they thought, already stamped on his face. The two slaves were
purchased, I believe, from a trader: it has been impossible, therefore,
for me to ascertain where Tom was born, or when. Georgia field-hands
are not accurate as Jews in preserving their genealogy; _they_ do
not anticipate a Messiah. A white man, you know, has that vague hope
unconsciously latent in him, that he is, or shall give birth to, the
great man of his race, a helper, a provider for the world's hunger: so
he grows jealous with his blood; the dead grandfather may have presaged
the possible son; besides, it is a debt he owes to this coming Saul to
tell him whence he came. There are some classes, free and slave, out of
whom society has crushed this hope: they have no clan, no family-names
among them, therefore. This idiot-boy, chosen by God to be anointed with
the holy chrism, is only "Tom,"--"Blind Tom," they call him in all the
Southern States, with a kind cadence always, being proud and fond
of him; and yet--nothing but Tom? That is pitiful. Just a
mushroom-growth,--unkinned, unexpected, not hoped for, for generations,
owning no name to purify and honor and give away when he is dead. His
mother, at work to-day in the Oliver plantations, can never comprehend
why her boy is famous; this gift of God to him means nothing to her.
Nothing to him, either, which is saddest of all; he is unconscious,
wears his crown as an idiot might. Whose fault is that? Deeper than
slavery the evil lies.

Mr. Oliver did his duty well to the boy, being an observant and
thoroughly kind master. The plantation was large, heartsome, faced the
sun, swarmed with little black urchins, with plenty to eat, and nothing
to do.

All that Tom required, as he fattened out of baby- into boyhood, was
room in which to be warm, on the grass-patch, or by the kitchen-fires,
to be stupid, flabby, sleepy,--kicked and petted alternately by the
other hands. He had a habit of crawling up on the porches and verandas
of the mansion and squatting there in the sun, waiting for a kind word
or touch from those who went in and out. He seldom failed to receive it.
Southerners know nothing of the physical shiver of aversion with which
even the Abolitionists of the North touch the negro: so Tom, through his
very helplessness, came to be a sort of pet in the family, a playmate,
occasionally, of Mr. Oliver's own infant children. The boy, creeping
about day after day in the hot light, was as repugnant an object as the
lizards in the neighboring swamp, and promised to be of as little use to
his master. He was of the lowest negro type, from which only field-hands
can be made,--coal-black, with protruding heels, the ape-jaw,
blubber-lips constantly open, the sightless eyes closed, and the head
thrown far back on the shoulders, lying on the back, in fact, a habit
which he still retains, and which adds to the imbecile character of
the face. Until he was seven years of age, Tom was regarded on the
plantation as an idiot, not unjustly; for at the present time his
judgment and reason rank but as those of a child four years old. He
showed a dog-like affection for some members of the household,--a son
of Mr. Oliver's especially,--and a keen, nervous sensitiveness to the
slightest blame or praise from them,--possessed, too, a low animal
irritability of temper, giving way to inarticulate yelps of passion when
provoked. That is all, so far; we find no other outgrowth of intellect
or soul from the boy: just the same record as that of thousands of
imbecile negro-children. Generations of heathendom and slavery have
dredged the inherited brains and temperaments of such children tolerably
clean of all traces of power or purity,--palsied the brain, brutalized
the nature. Tom apparently fared no better than his fellows.

It was not until 1857 that those phenomenal powers latent in the boy
were suddenly developed, which stamped him the anomaly he is to-day.

One night, sometime in the summer of that year, Mr. Oliver's family were
wakened by the sound of music in the drawing-room: not only the simple
airs, but the most difficult exercises usually played by his daughters,
were repeated again and again, the touch of the musician being timid,
but singularly true and delicate. Going down, they found Tom, who had
been left asleep in the hall, seated at the piano in an ecstasy of
delight, breaking out at the end of each successful fugue into shouts of
laughter, kicking his heels and clapping his hands. This was the first
time he had touched the piano.

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