There is now living in Germany an individual who bears the name of a woman; but learned physicians have decided that the person is as much man as woman, having the organs of both sexes. What is still more curious, this person has the feelings of both sexes, having loved at first a man, and afterward a woman. There have been observed, also, a very few instances of individuals in whom the sexual organs of neither sex were present. It thus appears that a person may be of both sexes or of no sex at all.
Sex in Plants.—To one unacquainted with the mysteries of plant life and growth, the idea of attaching sexuality to plants seems very extraordinary; but the botanist recognizes the fact that the distinctions of sex are as clearly maintained in the vegetable as in the animal kingdom. The sexual organs of the higher orders of plants are flowers. That part of the flower which produces seeds answers to the female; another part, which is incapable of forming seeds, answers to the male. The fertile and sterile flowers are sometimes produced on separate plants. Very frequently, they are produced upon separate parts of the same plant, as in the oak, walnut, and many other forest trees, and Indian corn. In the latter plant, so familiar to every one, the "tassel" contains the male flowers, and the part known as the "silk," with the portion to which it is attached—which becomes the ear—the female or fertile flowers.In a large number of species, the male and female organs are combined in a single flower, making a true hermaphrodite.
Sex in Animals.—As previously remarked, individuals of opposite sex usually differ much more than in the character of their sexual organs only. Among higher animals, the male is usually larger, stronger, and of coarser structure than the female. The same contrast is observed in their mental characters. With lower animals, especially insects, the opposite is often observed. The female spider is many times larger than the male. The male ant is small in size when compared with the female. Nevertheless, in all classes of animals the difference in the structure and the functions of the sexual organs is the chief distinguishing character. These differences are not so great, however, as they might at first appear. The male and female organs of reproduction in man and other animals, which seem so dissimilar, when studied in the light shed upon this subject by the science of embryology, are found to be wonderfully alike in structure, differing far more in appearance than in reality, and being little more than modifications of one general plan. Every organ to be found in the one sex has an analogue in the other which is complete in every particular, corresponding in function, in structure, and usually in position.
Other Sexual Differences.—In this country there is between five and six inches difference inheight and about twenty pounds difference in weight between the average man and the average woman, the average man being about five feet, eight inches in height, and weighing one hundred and forty-five pounds; while the average woman is five feet, two or two and one-half inches in height, and weighs one hundred and twenty-five pounds. The relation of the sexes in height and weight varies in degree in different countries, but is never changed. The average height and weight of American men and women is considerably above that of the average human being.
Men and Women Differ in Form.—The differences in form are so marked that it is possible for the skilled anatomist to determine the sex of a human being who has been dead for ages, by an examination of the skeleton alone. In man, the shoulders are broad, the hips narrow, and the limbs nearly straight with the body. In woman, the shoulders are narrow and usually rounded, and set farther back, the collar-bone being longer and less curved, giving the chest greater prominence; while the hips are broad.
The consequence of these differences is that woman is generally less graceful and naturally less skillful in the use of the extremities than man, and hence less fitted for athletic sports and feats requiring great dexterity. A girl throws a stone awkwardly, less from want of practice than from a natural peculiarity of physical structure. Awoman walks less gracefully than a man, owing to the greater relative breadth of her hips, requiring a motion of the body together with that of the limbs. In consequence of this peculiarity, a woman is less fitted for walking long distances.
Modern Mania for Female Pedestrianism.—Nothing could be much more inhuman than the exhibitions made in satisfying the mania for female pedestrianism which has recently arisen. Not long since, in walking down one of the principal streets of Boston, we passed, in going a distance of thirty rods, three illuminated placards announcing to the public that in as many different public halls four female pedestrians were exhibiting their walking talents for the gratification of the crowds of bawdy loafers and jockeys who congregated to criticize their several "points," and bet on their walking capacity, as though they were horses on a race-course or hounds on a fox hunt.
3,000 Quarter Miles in 3,000 Quarter Hours.—We visited the halls and ascertained that two of these misguided women were attempting the feat of walking respectively 2,700 and 3,000 quarter miles in an equal number of successive quarter hours. This would require almost incessant exertion for nearly twenty-eight days in one case, and for more than thirty-one days in the other, without at any time a period of unbroken rest longer than ten minutes. Such a procedure, in the light of physiology, is a greater inhumanity than themost merciless Boston teamster would inflict upon his dumb brutes. Why does not Mr. Bergh exercise his function in such cases? We did not wonder that the poor women looked pale and suffering, and trudged along with a limping gait.
A Female Walking Match.—At another hall we found two women engaged in a "walking match." The hall was so crowded with spectators—with very few exceptions of the male sex—that it was with difficulty the narrow track could be kept clear.
The sixty hours for which the walk was to be continued had nearly expired, and the excitement grew more intense each moment. One of the walkers, who was a few miles in advance, strode on at a pace almost marvelous, constantly stimulated to greater efforts by the coarse shouts of the masculine audience, who evidently took the same sort of interest in the proceeding that they would in a dog race or a cock fight. The other was pale and spiritless, and it seemed with difficulty that she dragged herself along to keep upon the track until the last. At times she seemed to be almost fainting, as the result of the long-continued excitement and fatigue; but she managed to keep going until nine minutes before the slow moving clock had measured off the sixty hours, when she became too ill to be longer able to stand, and was carried off the track.
The cheers for the winner were as vigorous asthough a rebel fort had been captured, a million people emancipated from slavery, or some great and noble deed of honor or daring had been done; but no one thought of the injury which had been done the contestant. We turned away in disgust.
The ancient Greeks and Romans amused themselves with witnessing the gladiatorial contests of their male slaves; but it was left for civilized America to introduce woman into the "ring" and make her show her paces on the race-course. An ungraceful figure she cuts, and a repulsive spectacle she presents; and worst of all is the havoc which she makes with her health. At the very time that these four female pedestrians were making their disgraceful exhibit in Boston, in another part of the same city lay a helpless invalid who was once as noted a "female walkist" as any of them, made hopelessly ill by the same disregard of the plainest laws of nature.
The Male and the Female Brain.—But there are other important physical differences to which we must call attention. Man possesses a larger brain than woman, but she makes up the deficiency in size by superior fineness in quality. The female brain differs from the masculine organ of mentality in other particulars so marked that one who has given the subject attention can determine with perfect ease the probable sex of the owner of almost any skull which might be presented to him. This difference in the conformation of the skull isundoubtedly due to a difference in mental character, which, in turn, depends upon a difference in cerebral development. Faculties which are generally largely developed in one are usually smaller in the other, and the reverse.
Vital Organs of Man and Woman.—The anatomist also observes an interesting difference in the size of the various vital organs. For example, while a woman has a heart proportionally smaller than the same organ in man, she has a larger liver. Thus, while less well fitted for severe physical exertion by less circulatory power, she has superior excretory powers.
Woman Less Muscular, More Enduring.—This peculiarity of structure is perfectly harmonious with the fact which experience has established so often as to make the matter no longer a question, that woman is less fitted for severe muscular exertion than man, but possesses in a superior degree the quality known as endurance. With a less robust frame, a more delicately organized constitution, she will endure for months what would kill a robust man in as many weeks. More perfect elimination of the wastes of the body secures a higher grade of vitality. On no other hypothesis could we account for the marvelous endurance of the feminine part of the civilized portion of the human race, ground down under the heel of fashion for ages, "stayed," "corseted," "laced," and thereby distorted and deformed in a manner thatwould be fatal to almost any member of the masculine sex.
A Pathological Difference.—Most physiologists mention another particular in which woman differs materially from man; viz, in naturally employing, in respiration, chiefly the upper part of the lungs, while man breathes chiefly with the lower part of the lungs. For several years we have carefully studied this question, and we have been unable to find any physiological or anatomical reason sufficient to account for this fact, if it be such.
Why a Woman Does not Breathe Like a Man.—It is undoubtedly true that most women do breathe almost exclusively with the upper part of the chest; but whether this is anaturalpeculiarity, or an acquired, unnatural, and depraved one, is a question which we are decidedly inclined to answer in harmony with the latter supposition, basing our conclusion on the following undeniable facts:—
1. In childhood, and until about the age of puberty, respiration in the boy and the girl is exactly the same.
2. Although there is a change in the mode of respiration in most females, usually soon after the period of puberty, marked by increased intercostal respiration and diminished abdominal or deep respiration, this change can be accounted for on other than physiological grounds.
3. We believe the cause of this modification ofrespiration is the change in dress which is usually made about that time. The young girl is now becoming a woman, and must acquire the art of lacing, wearing a corset, "stays," and sundry other contrivances by means of which to produce a "fine form" by distorting and destroying all natural grace and beauty in the "form divine."
4. We have met a number of ladies whose good fortune and good sense had delivered them from the distorting influence of corset-wearing and tight-lacing, and we have invariably observed that they are as capable of deep respiration as men, and practice it as naturally.
We are thoroughly convinced that this so-called physiological difference between man and woman is really a pathological rather than a natural difference, and is due to the evils of fashionable dress, which we have exposed at some length in another work exclusively devoted to that subject.[2]In short, we believe that the only reason why women do not, under ordinary circumstances, breathe as do men, is simplybecause they can notbreathe naturally.
2 "Evils of Fashionable Dress, and How to Dress Healthfully."
The Reproductive Elements.—As has been previously observed, in all except the very lowest forms of life, two elements are necessary to the production of a new individual, or a reproduction of the species—a male element and a female element. The special organs by means of whichthese elements are produced, brought together, and developed into the new individual in a more or less perfect state, are termedsexual organs, as we have already seen. As an introduction to the specific study of the sexual organs in the human species, let us briefly consider the
Sexual Organs of Plants.—As already remarked, flowers are the sexual organs of plants. Nothing is more interesting in the natural world than the wonderful beauty, diversity, and perfect adaptability to various conditions and functions, which we see in the sexual parts of plants. An exceedingly interesting line of study, which has occupied the attention of many naturalists, is the wonderful perfection displayed in the adaptability of the male and female parts of plants to each other. Without burdening the reader with unnecessary technicalities of detail, we will briefly notice the principal parts of vegetable sexual organs as illustrated in flowers.
Complete flowers are made up of four parts, two of which, thestamenandpistil, are essential, while the other two, the calyx and corolla, are accessory.
Thecalyxis that part which surrounds the flower at its outer and lower part. It varies greatly in form and color, but is most frequently of a green or greenish color.
Just within the calyx is thecorolla, which usually forms the most attractive, showy, and beautiful part of the flower. The beautifully coloredpetals of the rose, geranium, dahlia, and other similar flowers, form their corollas.
Vegetable Husbands.—Within the cup formed by the calyx and corolla are placed thestamensandpistilsof the flower, the first being the male organs proper, and the second the female organs of the flower.
The stamen is composed of a stem or filament, at the summit of which are placed two little sacks called theanther, which contain a fine, microscopic dust, thepollen, which contains the male reproductive element of the flower. This part of the plant corresponds to the male organ of reproduction in animals. A stamen has been called, not inaptly, a vegetable husband. Some flowers have many stamens, or vegetable husbands, which reminds us of the custom in Thibet and some other Eastern countries which allows a woman to have several husbands.
Polygamous Flowers.—The great naturalist, Linnæus, whose name was immortalized by his careful study and classification of organized life, made the number of stamens possessed by various flowers the basis of a systematic classification.
For example, a flower having but one stamen was classed asmonandria, which means, literally, one husband; one having two stamens was classified asdiandria; flowers having a large number of male organs were termedpolyandria, or many husbands.
The Female Organ of Flowers.—Thepistiloccupies the very center of the flower. It produces and contains in a cell, the female element, termed theovule. It is surmounted by thestyleand thestigma.
A series of plants in which the sexual organs are not visible to the eye are termedcryptogamia, which means literally, hidden marriages.
As we proceed to study the anatomy of the human sexual apparatus we shall be constantly struck with the remarkable correspondence between animals and vegetables in the structure and functions of the sexual apparatus.
Sexual Organs of Animals.—The male reproductive element is called aspermatozoönorzoösperm. The female element is called anovum, literally, an egg.
The Spermatozoön.—The male reproductive element of animals is formed by an organ called thetestis, ortesticle, of which each male possesses two. They are elastic, glandular bodies, and are formed within the cavity of the abdomen, near the kidneys, but usually pass out of the abdominal cavity and descend to their permanent position before birth. The opening in the abdominal wall is usually completely closed in a short time; but occasionally it remains open, giving rise to congenital hernia, an accident in which a loop of intestine follows the testicle down into the scrotum, either completely or partially. In a few animals, as in theporcupine, the opening is never fully closed, and the testis remains in the cavity of the body most of the time, passing out only at certain periods. We also occasionally meet cases of human beings in which the testes have never descended from their place in the abdominal cavity, giving the individuals the appearance of eunuchs. This condition, however, though an abnormal one, does not in any way interfere with the function of the organs, as those who happen to possess it often imagine. We have also met with cases in which the organs were movable, and could readily be pressed up into the abdominal cavity, through the unclosed inguinal cavity, which afforded them a passage downward in the process of development.
As before remarked, these peculiarities do not affect the functions of the organs in any appreciable degree, although they not infrequently give rise to some apprehension on the part of those subject to them. The left testicle is sometimes a little smaller than the right, another fact which is seized upon by quacks as a means of exciting the fears of young men who have been addicted to bad habits, although the peculiarity is generally without important significance.
The testicles are connected with the urinary passage by means of two ducts which terminate near the base of the bladder, at which point they connect with the urethra. We need not dwell atfurther length upon the structure of the testicles, as this subject receives fuller attention elsewhere.
Human spermatozoa are about 1/600 of an inch in length. Those of reptiles are very much larger. One of the remarkable features of these minute elements is their peculiar movements. While alive, the filamentous tail is in constant action in a manner strongly resembling the movements of the caudal appendage of a tadpole. This wonderful property led the earlier observers to believe that they were true animalcula. But they are not to be regarded as such, though one can scarcely make himself believe otherwise while watching their lively evolutions, and apparent volitionary movement from one point to another.
Spermatozoa originate in the testis as cells, which are filled with granules. After a time, each granule acquires a long appendage, and then the cell has become converted into a bundle of small zoösperms. Development still continues, until finally the thin pellicle on the outside of the bundle is ruptured, thus liberating the young spermatozoa, which speedily complete their full development. The spermatozoön is pure protoplasm, which is the basis of all life, and its power of spontaneous motion is due to this fact.
In man, the formation of spermatozoa continues with greater or less rapidity from puberty to old age, though at the two extremes of existence they are imperfectly developed. When notdischarged from the body, they are said to be absorbed. Some physiologists claim that they are composed of a substance identical with nerve tissue, and that by absorption they play a very important part in the development and maintenance of the nervous system.
It is asserted by good authorities that the reproductive element in man is not so well developed as to be really fit for the reproduction of the species before the age of twenty-four or twenty-five. After the age of forty-five or fifty, the reproductive elements deteriorate in quality, and become again unfitted for vigorous procreation.
The fully developed zoösperms are suspended in a transparent, gelatinous fluid, which, mingled with the secretion of the prostate gland and other fluids which it meets during its expulsion from the body, constitutes thesemen.
The Ovum.—The female element of generation, the ovum, is produced by an organ called theovary, of which there are two in each individual. In size and form, the ovary closely resembles the testicle. Like the latter organ, also, it is formed within the body early in the process of development; but instead of passing outward and downward, as does the testicle, it remains within the abdominal cavity, suspended in place by ligaments. It is connected with a duct which receives the ovum as it is discharged, and conveys it to the uterus.
The human ovum varies in size from 1/240 to 1/120 of an inch in diameter, and consists of a single cell. Ova are not formed in such large numbers as zoösperms. As a general rule, in the human female, a single ovum is developed and discharged once in about four weeks, during the period of sexual activity.
Fecundation.—It is often asked, and the question has elicited some discussion, Which is the principal reproductive element; the zoösperm, or the ovum? The ancients supposed the male element to be the essential element, being simply nourished and developed by the female; but modern research in biological science does not sustain this view. Probably neither one enjoys especial preëminence; for neither can undergo complete development without the other. In very rare cases, the ovum has been observed to undergo a certain amount of development of itself; but a perfect individual can be produced only by the union of the two kinds of elements, which process is known asfecundation. The instant this union occurs, the life of a new individual begins. All the changes which result between that moment and the birth of the individual are those of development only. Indeed, the same existence continues from the instant of the union of the two elements, not only until birth, but through growth, the attainment of maturity, the decline of life, and even until death.
It is interesting to observe the different methods by which fecundation is effected, both in plants and animals, for this is a process common to both.
Fecundation in Flowers.—The great naturalist, Linnæus, was the first to explain the reproductive process in plants. He tells us that "the flower forms the theater of their amours; the calyx is to be considered as the nuptial bed; the corolla constitutes the curtains; the anthers are the testes; the pollen, the fecundating fluid; the stigma of the pistil, the external genital aperture; the style, the vagina, or the conductor of the prolific seed; the ovary of the plant, the womb; the reciprocal action of the stamens on the pistil, the accessory process of fecundation."
Thus marvelous is the analogy between the reproductive organs and their functions in plants and animals. Through this one vital process we may trace a close relation between all the forms of life, from the humblest plant, or even the mere specks of life which form the green scum upon a stagnant pool, to man, the masterpiece of creation, the highest of all animated creatures. In all the realm of Nature there can be found no more remarkable evidences of the infinite skill and wisdom of the Creator of all things.
In many instances the action of plants seems almost to be prompted by intelligence. At the proper moment, the corolla contracts in such a way as to bring the stamens nearer to the stigma, or incontact with it, so as to insure fecundation. In some aquatic plants the flowers elevate themselves above the surface of water while the process of fecundation is effected; submerging themselves again immediately afterward.
Other very curious changes occur in flowers of different species during the reproductive act. The stigma is observed to become moistened, and even to become distinctly odorous. Often, too, it becomes intensely congested with the juices of the plant, and sometimes even acquires an uncommon and most remarkable degree of contractility. This is the case with the stigma of the tulip and one variety of sensitive plant, and is in these plants observed to occur not only after the application of the pollen to the stigma, but when excited by any other means of stimulation. The flowers of some plants, during and after fecundation, also show an increase of heat, in some cases so marked as to be readily detected with the thermometer. This is said to be the case with thearumof Italy.
In some plants in which the pistil is longer than the stamens, thus elevating the stigma above the anthers, the female organ is often observed to bend over and depress itself so as to come within reach of the anthers.
In most instances the fecundation of flowers is chiefly effected through a purely mechanical process, though in these cases also we see a wonderful adaptation of parts to conditions.
When the male and female parts of flowers are situated on different plants, as is the case in the willow, the poplar, the melon vine, and many other species, the pollen of the male flower is wafted by the wind or gentle breeze to the stigma of the female flower, which will usually be found at no very great distance, although fertilization may take place in this way at very considerable distances. Bees, moths, and many other species of insects, serve a very important purpose in this work, transporting the fertilizing dust upon their wings, antennæ, sucking-tubes, and feet. Small birds, and even the humble snail, which would scarcely be credited with any useful function, are also very serviceable in the same direction. The part performed by insects in the reproductive process of many plants is so great that they have been very poetically termed "the marriage priests of flowers."
Nature provides for thorough fecundation in these cases by placing the plants which bear the male and the female flowers near each other. This fact accounts for the unproductiveness of certain varieties of strawberries unless mixed with plants of some other variety, it being well known to nursery-men that some varieties produce only the female parts of flowers.
Modes of Fecundation in Animals.—The modes by which fecundation is effected in animals are still more various and wonderful than in plants.In some of the lower animals, as in most fish and reptiles, both elements are discharged from the bodies of the parents before coming in contact, there being no contact of the two individuals. In this class of animals the process is almost wholly analogous to fecundation in those plants in which the male and female flowers are on different plants or different parts of the same plant. In the female fish, a large number of ova are developed at a certain season of the year known as the spawning season. Sometimes the number reaches many thousands. At the same time, the testicles of the male fish, which are contained within the abdominal cavity, become distended with developed zoösperms. When the female seeks a place to deposit her eggs, the male closely follows; and as she drops them upon the gravelly bottom, he discharges upon them the zoösperms by which they are fecundated. The process is analogous to some species of frogs. When the female is about to deposit her eggs, the male mounts upon her back and rides about until the eggs are all deposited, discharging upon them the fertilizing spermatozoa as they are laid by the female.
In higher orders of animals, fecundation takes place within the generative organs of the female by contact between the male and the female organs. To effect this, there are necessitated certain accessory organs, thepenisin the male and thevaginain the female.
Nothing in all the range of nature is more remarkable than the adaptation of the two varieties of sexual organs in each species. This necessary provision is both a powerful means of securing the perpetuation of the species, and an almost impassable barrier against amalgamation.
The act of union, or sexual congress, is calledcoitusorcopulation. It is accompanied by a peculiar nervous spasm due to excitement of special nerves principally located in thepenisin the male, and in an extremely sensitive organ, theclitoris, in the female. The nervous action referred to is more exhausting to the system than any other to which it is subject.
Union of the Ovum and Zoösperm.—The zoösperms not only come in contact with the ovum, but penetrate the thin membrane which incloses its contents, and enter its interior, where they disappear, becoming united with its substance. In the ova of certain fishes, small openings have been observed through which the spermatozoa find entrance. Whether such openings exist in human ova is an undecided question; but it is probable that they do.
Curious Modes of Reproduction.—A peculiar kind of reproduction is observed in a variety of polyp, a curious animal which very much resembles a shrub in appearance. It attaches itself to some solid object, and then, as it grows, sends out little protuberances resembling buds. Some ofthese separate and fall off, swimming about as separate animals. These never become like the parent polyp; but they lay eggs, which hatch, and become stationary polyps like their grandparent, and in their turn throw off buds to form swimming polyps. In this case we have two kinds of generation combined, alternating with each other.
Plant-lice afford a curious illustration of a similar generation. Males and females unite and produce eggs. The creatures produced by the hatching of eggs are neither males nor perfect females. They areimperfect females. They are all alike, so that no sexual union occurs. Instead of laying eggs, they produce live young like themselves, which appear to be developed from internal buds similar to the external buds of the polyp. After this method of reproduction has continued for eight or ten generations, a few perfect individuals appear, and the first process is repeated.
The common honey-bee affords another illustration like the last. A virgin queen sometimes lays eggs, which always produce males, or drones. After union with a male, she lays eggs in the royal cells which become perfect females like herself. She also seems to have the power to lay, at will, unfecundated eggs, from which drones are produced.
Human Beings Are Developed Buds.—It has been very aptly suggested by an eminent physiologist that the ovum and zoösperm may be correctlyconsidered as internal buds. Thus it would appear that generation is universally a process of budding. A child is but a compound bud, an offshoot from its parents. This idea is not a mere fancy, but has a scientific basis. As all the exquisite details of the most beautiful flower are in essence contained within the tiny bud which first makes its appearance, so is the developed human being, the full-grown man or woman, virtually contained within the tiny cell called the ovum after it has been impregnated or fecundated by the zoösperms. In short, men and women are blossoms in a strictly scientific sense.
Fecundation in Hermaphrodites.—The process of fecundation in hermaphrodite animals is very peculiar. In some cases, as in the snail, the union of two individuals is usually necessary, though each possesses both kinds of organs. In other cases, as in the tape-worm, the oyster, and numerous other mollusks, a single individual has the power to fertilize its own ova, thus being wholly independent. Human hermaphrodites are usually so deformed that fecundation is not effected, which is a fortunate safeguard against the multiplication of such monstrosities.
Development.—After the union of the two elements, known as fecundation orconception, if the conditions are favorable, development occurs, and the little germ is in due process of time developed into an individual which is an exact counterpartof its parents. During this developmental process, the embryonic being is variously treated by different classes of animals.
Unprotected Development.—Most fishes and reptiles discharge their ova before fecundation, or soon after, and pay no further attention to them. The fish deposits its eggs in a little hollow scooped out in the gravelly bed of a stream, or sows them broadcast upon the waters. The turtle buries its eggs in the sand, and leaves them to be hatched by the sun. The ostrich disposes of her eggs in the same way. Many other species of animals pay no regard to the protection of the germs which are destined, if placed under favorable conditions, to become individuals like themselves.
Partial Protection of the Ovum.—There are some exceptions, however, to this general rule among fishes and reptiles. Even fishes manifest a degree of parental solicitude in certain cases. The male of a species of South American fish gathers up the eggs after fecundation has taken place, and carries them in his mouth until they are hatched. Another male fish carries the eggs of his mate in a little pouch upon the lower and posterior part of his body.
Certain species of frogs carry their eggs wound about their legs; others suspend them from the abdomen. Another variety carries its young upon its back. Prof. Wyman describes a "swamp toad" which patiently takes the eggs of his mate, one byone, and fastens them upon her back, observing great regularity in arrangement. These several devices are evidently for the purpose of protecting, in some degree, the young individual during the helpless stage of its existence.
Development in the Higher Animals and Man.—Higher animals are less prolific, and their development is a more complicated process; hence, their young need greater protection, and, for this reason, the ova, instead of being discharged from the body of the female after fecundation, are retained.[3]As we have seen that a suitable receptacle is sometimes provided outside of the body, so now a receptacle is needed, and is provided in the interior of the body of the female. This receptacle is called
3 Curious examples of internal development sometimes occur in animals which usually deposit eggs. Snakes have been known to produce both eggs and living young at the same time. At the annual meeting of the American Society for the Advancement of Science, at Detroit, Mich., in August, 1875, we had the pleasure of examining a specimen, exhibited by Prof. Wilder, of a chick which had undergone a considerable degree of development within the ovary of the hen. It had a head, a rudimentary brain, and internal viscera, but no feathers nor limbs. It was, in fact, an egg hatched before it had been laid. The anomaly excited much interest at that time and since among biologists.
The Uterus.—This is a hollow, pear-shaped organ, located in the median line, just behind the bladder, between it and the rectum. It is supported in place by various ligaments and by thejuxtaposition of other organs. Its larger end is directed upward, and communicates upon each side with a very narrow tube which is prolonged outward on either side until it nearly touches the ovary of the same side. Its lower and smaller end fills the internal extremity of the passage previously described as the vagina. When an ovum is matured, it escapes from the ovary into the narrow tube referred to, called theFallopian tube, and passes down into the cavity of the uterus. If fecundation does not occur, it is expelled or absorbed after six to twelve or fourteen days. If copulation occurs, however, zoösperms are brought into the cavity of the uterus, and, coming in contact with the ovum, fecundate it. This isconception. When the natural process is allowed to proceed, development occurs.
Uterine Gestation.—This is the term applied to the process last referred to. We shall not attempt to describe in detail this most wonderful and intricate of all living processes; but will sketch only the chief points, leaving the reader who would obtain a more complete knowledge of the subject to consult any one of the numerous physiological and obstetrical works which deal with it in a very exhaustive manner.
As soon as the ovum is impregnated by the male element, it begins a process of symmetrical division. The first division produces two cells out of the single one which first existed. By the nextdivision, four segments are produced; then eight, sixteen, etc. While this process is going on, the ovum becomes adherent to the internal wall of the uterus, and is soon enveloped by its mucous membrane, which grows up about and incloses it.
The Primitive Trace.—When the process of segmentation has advanced to a certain point, the cells are aggregated together in a compact layer at the surface. Soon a straight line appears upon this layer, which is called theprimitive trace. This delicate line becomes the basis for the spinal column; and upon and about it the whole individual is developed by an intricate process of folding, dividing, and reduplication of the layer of cells. One end of the line becomes the head, and the other becomes the tail. Even man has a caudal appendage at an early stage of his existence. After a further lapse of time, little excrescences, buds, or "pads," appear in the proper positions to represent the arms and legs. After further development the ends split up into fingers and toes, and by the continued development of the parts, perfect arms and legs are formed.
Curious Relation to Lower Animals.—It is a very remarkable fact that in the lower animals we have numerous examples in which the permanent condition of the individual is the same as some one of the stages through which man passes in the process of development. The same author previously quoted makes the following interesting statements:—
"The webbed feet of the seal and ornithorhynchus typify the period when the hands and feet of the human embryo are as yet only partly subdivided into fingers and toes. Indeed, it is not uncommon for the 'web' to persist to some extent between the toes of adults; and occasionally children are born with two or more fingers or toes united to their tips.
"With the seal and the walrus, the limbs are protruded but little beyond the wrist and ankle. With the ordinary quadrupeds, the knee and elbow are visible. The cats, the lemurs, and the monkeys form a series in which the limbs are successively freed from the trunk, and in the highest apes they are capable of nearly the same movements as the human arm and leg, which, in their development, passed through all these stages."
Simplicity of Early Structures.—The first structures formed are exceedingly simple in form. It is only by slow degrees that the great complicity which characterizes many organs is finally attained. For example, the heart is at first only a straight tube. By enlargement and the formation of longitudinal and transverse partitions, the fully developed organ is finally produced. The stomach and intestines are also at first but a simple straight tube. The stomach and large intestine are formed by dilatation; and by a growth of the tube in length while the ends are confined, the small intestines are formed. The other internal organs are successively developed by similar processes.
The Stages of Growth.—At first insignificant in size—a simple cell, the embryonic human being steadily increases in size, gradually approximating more and more closely to the human form, until, at the end of about nine calendar months or ten lunar months, the new individual is prepared to enter the world and begin a more independent course of life. The following condensation of a summary quoted by Dr. Austin Flint, Jr., will give an idea of the size of the developing being at different periods, and the rate of progress:—
At the end of the third week, the embryon is a little less than one-fourth of an inch in length.
At the end of the seventh week, it is three-fourths of an inch long. The liver, lungs, and other internal organs are partially formed.
At the eighth week, it is about one inch in length. It begins to look some like a human being, but it is impossible to determine the sex.
At the third month, the embryon has attained the length of two to two and one-half inches. Its weight is about one ounce.
At the end of the fourth month, the embryon is called a fetus. It is from four to five inches long, and weighs five ounces.
At the fifth month, the fetus is nearly a foot long, and weighs about half a pound.
At the sixth month, the average length of the fetus is about thirteen inches, and its weight one and a half to two pounds. If born, life could continue a few minutes.
At the seventh month, the fetus is from fourteen to fifteen inches long, and weighs two to three pounds. It is now viable (may live if born).
At the eighth month, the length of the fetus is from fifteen to sixteen inches, and its weight from three to four pounds.
At the ninth month, the fetus is about seventeen inches long, and weighs from five to six pounds.
At birth, the infant weighs a little more than seven pounds, the usual range being from four to ten pounds, though these limits are sometimes exceeded.
Duration of Gestation.—The length of time required for the development of a human being is usually reckoned as about forty weeks. A more precise statement places it at about two hundred and seventy-eight days. This limit is often varied from. Cases have occurred in which a much longer time has been required, and numberless cases have occurred in which human beings have been born several weeks before the expiration of the usual time, as stated. There is some uncertainty respecting the exact length of the period of gestation, which grows out of the difficulty of determining, in many cases, the exact time when conception takes place.
Uterine Life.—The uterine life of the new individual begins with the impregnation of the ovum, which occurs the instant it is brought in contactwith the zoösperms of the male. While in the uterus, the young life is supported wholly by the mother. She is obliged to provide not only for her own sustenance, but for the maintenance of her child. And she must not only eat for it, but breathe for it as well, since it requires a constant and adequate supply of oxygen before birth as much as afterward.
How the Unborn Infant Breathes.—Oxygen and nutriment are both supplied to it through the medium of an organ called theplacenta, which is a spongy growth composed almost entirely of blood-vessels, and is developed upon the inner wall of the uterus, at the point at which the ovum attaches itself after fecundation. The growing fetus is connected with this vascular organ by means of a sort of cable, called theumbilical cord. The cord is almost entirely composed of blood-vessels which convey the blood of the fetus to the placenta and return it again. The fetal blood does not mix with that of the mother, but receives oxygen and nourishment from it by absorption through the thin walls which alone separate it from the mother's blood.
The umbilical cord contains no nerves, as there is no nervous connection between the mother and the child. The only way in which the child can be influenced by the mother is through the medium of the blood, to changes in which it is very susceptible, as we shall see more clearly hereafter.
The cord is attached to the body of the child at the point called thenavel, being cut off at birth by theaccoucheur. With the placenta, it is expelled soon after the birth of the child, and constitutes the shapeless mass familiarly known as theafter-birth, by the retention of which the most serious trouble is occasionally caused.
Parturition.—At the end of the period of development, the young being is forcibly expelled from the laboratory of nature in which it has been formed. In other words, it is born; and this process is termedparturition. Though, at first thought, such an act would seem an utter impossibility, yet it is a very admirable illustration of nature's adaptation of means to ends. During the months of gestation, while the uterus has been enlarging to accommodate its daily increasing contents, the generative passages have also been increasing in size and becoming soft and distensible, so that a seeming impossibility is in due time accomplished without physical damage, though possibly not without intense suffering. However, it is a most gratifying fact that modern medical science may do much to mitigate the pains of childbirth. It is possible, by a proper course of preparation for the expected event, to greatly lessen the suffering usually undergone; and some ladies assert that they have thus avoided real pain altogether. Although the curse pronounced upon the feminine part of the race, in consequence of the sin of Eve, implies suffering inthe parturient act, yet there is no doubt that the greater share of the daughters of Eve are, through the perverting and degenerating influences of wrong habits and especially of modern civilization, compelled to suffer many times more than their maternal ancestor. We have sufficient evidence of this in the fact that among barbarian women, who are generally less perverted physically than civilized women, childbirth is regarded with very little apprehension, since it occasions little pain or inconvenience. The same is true of many women among the lower laboring classes. In short, while it is true that more or less suffering must always accompany the parturient act, yet the excessive pain usually attendant upon the process is the result of causes which can in many cases be removed by proper management beforehand and at the time of confinement.
After being relieved of its contents, the uterus and other organs rapidly return to nearly their original size.
Changes in the Child at Birth.—In the system of the child a wonderful change occurs at the moment of its expulsion into the outer world. For the first time, its lungs are filled with air. For the first time they receive the full tide of blood. The whole course of the circulation is changed, and an entirely new process begins. It is surprising in how short a space of time changes so marvelous can be wrought.