PRIMITIVE BELIEFS ABOUT FATHERLESS PROGENY
In the preceding chapter I related the curious and exceptional cases
of "fatherless reproduction" by means of true egg-cells, those cells
of special nature produced in the organs called "ovaries," present in
all but the simplest animals and plants. These egg-cells are usually,
with elaborate sureness and precise mechanism after liberation from
the ovary, fertilised by (that is to say, fused with) the complemental
reproductive cells--the sperm-filaments--produced by other
individuals, the males.
But we must not forget--and, indeed, one should not enter on the
consideration of this subject without a knowledge of the fact--that
vast numbers of animals and plants reproduce themselves "asexually,"
as it is termed, namely, by breaking-off or separating buds, branches,
or other good solid bits of their structure which, when thus
separated, are capable of individual life and growth. Thus plants very
largely multiply, using this method in addition to the sexual method
of egg-cells and sperm-cells. One may take "cuttings" from plants and
rear them, and plants also "cut" or detach such bits themselves, in
the form of runners, of dividing bulbs, of bulbules, and such
reproductive growths seen on the lily, on the viviparous, alpine
grass, and many other plants. Even a bit cut off from the leaf of a
plant (for instance, a begonia) will sprout, root itself, and grow
into a completely formed and healthy individual. Animals, too, such as
polyps or zoophytes, and many beautiful and elaborate worms, multiply
by "fission," dividing into two or more parts, each of which becomes a
complete animal. This process is not seen in any fish, amphibian,
reptile, bird, or mammal, nor in molluscs, nor in insects,
crustaceans, myriapods, and arachnids (spiders and scorpions). It is
almost wholly confined to lower animals (worms and polyps) and to
plants, and hence is often called "vegetative reproduction." The most
remarkable case of its appearance among higher forms is that of the
marine Ascidians, or tunicates--close allies of the true
vertebrates--where reproduction by budding and the formation of
wonderfully elaborate star-like forms produced by budding and the
cohesion of the budded individuals as one composite individual are
well known. Their beautiful shapes and colours have been reproduced in
hundreds of exquisite pictures by our great artist-naturalists. We
thus have to recognise that there are two distinct kinds of
reproduction in living things. One is "asexual," by means of division
or separation of large or special masses of their existence, made up
of ordinary tissue cells. Co-existing with this, often in the same
individuals, is the other method, the "sexual," by means of detached
egg-cells and sperm-cells which are thrown off from the parents, and
do not (except in rare instances) proceed to develop unless the
egg-cell is "fertilised" by the fusion with it of a sperm-cell.
The whole subject of the reproduction of animals and plants was, until
the introduction of the microscope, involved in obscurity and mystery.
The Greeks and Romans had necessarily very imperfect and erroneous
notions on the subject, and it was not until 300 years ago that
William Harvey, the discoverer of the circulation of the blood,
declared, as a general law, that every living thing is born from an
egg. During that 300 years his conclusion has been examined and
modified, corrected and expanded, and the microscope has at last
enabled us to see and follow the excessively minute particles and
structures by which sexual reproduction is effected. Harvey's dictum
was a step in advance when it was made, for previously the belief was
current that living things were "bred" in all sorts of queer ways. It
was supposed that the putrefying flesh of a dead animal actually was
converted by a sudden process into maggots, and that rotten wood
would breed, out of its own substance, ships' barnacles and even young
geese and mice--an opinion contested only 200 years ago by Sir Thomas
Browne! No difficulty was felt in admitting that whole swarms of
insects, fishes, and even herds of larger beasts were spontaneously
generated from mud, from putrid matter, or from the waters of the sea.
That, indeed, was the popular notion set forth by the poet, John
Milton, as to the mode in which living things were "miraculously"
brought into existence at the beginning of things by the "fiat" of the
Creator. What more probable than that such a creation should still be,
here and there, at work? However, not three centuries ago, actual
experiment gradually convinced the learned that maggots are bred in a
dead body only from the eggs laid by parent flies, as shown by the
Italian Redi in 1668 who found that no maggots were bred when he
simply excluded the flies from access to the dead body by covering it
with wire gauze, but that the blow-flies swarmed on the gauze and
vainly laid their eggs on it! It was only gradually recognised that
birth by means of eggs or germs extruded from parental organisms of
the same history and character as their offspring is the explanation
of all such swarms of flies, worms, and even mushrooms and moulds as
had been formerly ascribed to a mysterious power of breeding these
organisms possessed by inanimate dirt and refuse.
In spite of this progress in knowledge the belief in "spontaneous
generation" of such excessively minute organisms as the bacteria and
yeasts was general until Theodore Schwann in 1836 performed with them
just the same experiment as Redi had performed with blow-flies in
1668. He showed that if a putrescible liquid (for instance, soup) were
boiled in a retort so as to destroy all germs, and then the open neck
of the retort was kept heated in a flame, so that no floating germs
could enter alive, the soup did not putrefy, and no bacteria or other
organisms appeared in it. The old notions, nevertheless, survive to
this day. Peasants, fisher-folk, and even uneducated wealthy
countrymen cling to them with the confidence arising from profound
ignorance. And occasionally a man of some scientific training and
knowledge astonishes the world by a futile attempt to show that the
old fancies were true in regard, at any rate, to the lowest
microscopic forms of life. But these are but the echoes of the past;
we do not believe nowadays in "spontaneous generation," nor in sudden
transformations of lower into higher forms of life. The doctrine,
"_omne vivum e vivo_"--every living thing (in the present condition of
our earth) is born from a living thing--is now held by scientific
investigators as a reasonable generalisation of experience.
On the other hand, Harvey's dictum, "Every living thing comes from an
egg," is only true in a limited sense, namely, that whilst the
individual among most larger animals and plants is always traceable to
an egg-cell detached from a parental individual of a like kind of
species, there are whole groups and series of lower animals and most
plants in which the individual born or "developed" from an egg-cell
does not proceed when grown to full size to reproduce in turn by eggs
and fertilising sperms, but divides into two or more individuals or
gives off detached buds or reproductive bulbs, which become separate
individuals, and only after these and several successive generations
of individuals have been thus produced "asexually," by fission or by
budding, does a generation appear which produces true egg-cells and
sperm-cells and reproduces by their means. Thus it is true that the
individuals "budded off" or separated by fission from an asexual
parent can be ultimately traced through one or more generations of
previous asexual parents to an egg-cell produced and fertilised in the
regular way, and with this important modification Harvey's dictum is
justified. These facts and the wonderful histories of the animals and
plants in which egg-and-sperm-producing generations "alternate" with
generations which multiply by fission and budding have only been
worked out in detail and by the aid of the microscope during the great
century of scientific discovery which lies just behind us. Often the
two generations, reproducing, the one by fission, the other by egg and
sperm-cells, are alike in appearance, but often they are very
different, and have naturally been supposed at first to have nothing
to do with each other.
Thus some of the little "coralline polyps" and other most beautiful
little marine flower-like polyps attached to rocks, weeds, and shells
in the sea reproduce by budding and division. But after a period of
such growth and such budding they produce on their stalks--jelly-fish!
These jelly-fish are budded and thrown off by them, as glass-like
swimming bells, which lead an independent life, seize prey, nourish
themselves, and grow to a size varying from that of a sixpence to that
of a cart-wheel. These "bells" are commonly known as "jelly-fish."
They discharge thousands of egg-cells into the sea and fertilise them
with sperms! From those fertilised eggs grow young polyps, which fix
themselves to rocks or weeds, and grow up to bud and multiply by
fission, and eventually to produce again by fission a generation of
jelly-fishes! Such a marvellous history of alternating modes of
reproduction has been discovered, and described in greatest
microscopic detail and with most ample pictorial representations of
all the minutest structures of the organisms studied, not only in many
marine polyps, but also in the case of many parasitic worms, such as
the tape worms and the liver-flukes. Some of the most fascinating
cases, on account of the beauty of the little creatures concerned, are
found amongst the surface-swimming Ascidians of the sea--the
glass-like Salps. But our common ferns and mosses also show this same
alternation of sexual and sexless generations, the two generations
differing greatly in size, form, and structure from one another,
whilst the whole story of "flowers" and their structure is bound up
with a wonderful "telescoping" or rolling of the two generations
(sexless and sexual) into one plant!
It was not until long after Harvey's time that these things were
understood, and there was every excuse--in the absence of observation
of the facts, especially those yet to be revealed by the
microscope--for the erroneous suppositions and explanations which were
formerly entertained as to the mode of reproduction of the less
familiar plants and animals. If we go back to the starting-point of
European science, to the great Aristotle, we find that he had formed
singularly correct conclusions as to the reproduction of the larger
kinds of animals, though he knew nothing about "sperms," having no
microscope, and only regarded the fluid produced by male animals as
exercising a fertilising effect on the eggs, which in many instances
are large enough for anyone to see. But, of course, he could not have
any knowledge of the egg-cell, nor does he say anything about the
reproduction of plants. Later, however, the sexuality of flowering
plants was taught by his pupils, and at the time of the Roman Empire
there was a very definite belief among learned men (such as Pliny)
that the larger plants and animals reproduce by eggs or by seeds
produced by the females which require to be "fertilised" by a product
formed in the males--the spermatic fluid in the case of animals and by
the pollen in the case of a few flowering plants (_e.g._ the
date-palm). But there was no idea of holding this as a general and
universal law. From Pliny to Harvey and later, those who concerned
themselves with natural history accepted without difficulty any
strange accounts or appearances as to the reproduction or the sudden
production in fanciful and astonishing ways of the lower and smaller
animals and plants. They did not expect these inferior creatures to
have the same methods of reproduction as the higher and bigger
creatures. It is only now, since the later years of the nineteenth
century, that we are able to show that all animals and plants, even
the minutest microscopic kinds, reproduce by the formation and
separation of egg-cells, and that these egg-cells are (in all but a
few exceptional cases) fertilised by sperm cells, which are smaller
than the egg-cells, and usually provided with active swimming
filaments.
Not only did our mediaeval ancestors believe all sorts of fancies as to
the propagation of lower animals and plants, but they were quite
prepared to accept stories as to reproduction in the case of higher
animals, and even in mankind, by irregular methods, such as
parthenogenesis, or the defect of an ordinary male parent. In the
Middle Ages in Europe, and earlier in the East, the belief in the
frequent occurrence of the birth of a child which had no human male
parent was common. It was, so to speak, an admitted though irregular
occurrence. A very curious thing is that when such cases were supposed
to occur, they were not ascribed to any natural process such as we now
recognise in the "parthenogenesis" of insects and crustaceans, but to
the visitation of the mother by a spirit--a floating, volatile demon
or angel (known as an "incubus" in the Middle Ages) beneficent or
malicious as the case might be. Stories of the nocturnal visits of
these mysterious ghostly "incubi" are on record in great number and
variety, both in European and Oriental tradition and legend. There
seems to have been a readiness to believe the theory of paternity from
among the hidden world of goblins, fairies, and sprites which was very
naturally made use of by a woman and her relatives when she could not
produce the father of her child.
We come across examples of such beliefs in invisible agents of
paternity even among the more cultivated Romans. Thus Virgil in his
"Georgics" cites as a fact that mares are fertilised by the wind. His
words are given on the next page.
It is now known that, quite apart from any motive of concealment of
the true paternity of their offspring, some of the native tribes of
Australia have the belief that, as the regular and normal thing,
children are begotten by strange fairy-like spirits which haunt the
rocks and trees of certain localities and enter the future mother as
she passes by these haunted rocks and trees. These Australian "black
fellows" hold that the human father counts for nothing in the matter.
The belief of these Australian savages is referred to by writers on
the subject (Mr. Andrew Lang and others) as "the spiritual theory of
conception." There are some reasons for thinking that this curious
theory and the accompanying ignorance as to the natural causes of
conception were widely spread among primeval men. The fact that most
trees are fertilised by the wind (which carries to their female
flowers the invisible powder, or pollen, of the male flowers,
conveyed in the case of smaller plants which have gay-coloured flowers
by bees and butterflies) may have been noticed by primitive man, and
have started the belief that there are fertilising spirits or demons
in the air. However the fancy arose, it is only a parallel to the
strange fancies as to spontaneous generation of all sorts of animals
and plants current 200 years ago among civilised men. And, further, it
is worth noting that the uncanny belief in the "incubus" which was
generally prevalent in the Middle Ages may possibly be considered as a
survival in (or incursion into) Europe of the primitive spiritual
theory of all human conception, and of the fertilising activity of the
haunting spirits of the air which was held by primeval man, and is
still found in full force among the Arunta tribes of Australia.
"Ore omnes versae in Zephyrum stant rupibus altis
Exceptantque leves auras et saepe sine ullis
Conjugiis vento gravidae, mirabile dictu."
Georgic iii. 275.
(Facing the west on lofty rocks
All stand and sniff the buoyant breeze
And often--marvellous to tell--
Without conjunction with a sire,
Bear young engendered by the wind.)