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 mediÆval 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.