HERMAPHRODITIC REPRODUCTION.
We have said that two kinds of cells represent reproduction, namely, sperm and germ-cells. These may be furnished by different individuals, or both may be found in one. When both are found in the same individual, the parent is said to be a _natural hermaphrodite_. A perfect hermaphrodite possesses the attributes of both male and female--uniting both sexes in one individual. Natural hermaphroditic reproduction occurs only among inferior classes of animals, and naturalists inform us that there are a greater number of these than of the more perfect varieties.
These are found low in the scale of animal organization, and one individual is able to propagate the species. In the oyster and ascidians no organs can be detected in the male, but in the female they are developed. Polyps, sponges, and cystic entozoa, may also be included among hermaphrodites.
It is only very low organisms indeed in which it is a matter of indifference whether the united sperm-cells and germ-cells are those of the same individual, or those of different individuals. In more elaborate structures and highly organized beings, the essential thing in fertilization is the union of these cells specially endowed by _different_ bodies, the unlikeness of derivation in these united reproductive centers being the desideratum for perpetuating life and power.
In other classes, as _entozoa_, there appear to be special provisions whereby the sperm-cells and germ-cells may be united; _i.e._, the male organs are developed and so disposed as to fecundate the ova of the same individual. Sexual and non-sexual modes of reproduction are illustrated by that well-defined group of marine invertebrate animals, called _cirripedia_ Fig. 98 represents one of this genus.
[Illustration: Fig. 98.
Pollicipes Mitella.]
Some of these are not only capable of self-impregnation, but likewise have what are called _complemental males_ attache to some of the hermaphrodites. In the whole animal kingdom, it may be doubted if there exists another such class of rudimentary creatures as the parasitic males, who possess neither mouth, stomach, thorax, nor abdomen. After exerting a peculiar sexual influence, they soon die and drop off; so that in this class of animals may be found the sexual distinctions of male, female, and perfect hermaphrodites.
[Illustration: Fig. 99.
Rotiferia; Brachionus Urceolaris; largely magnified. ]
There is a class of wheel-animalcules termed _rotifera_, of which the revolving volvox is one example. They have acquired this name on account of the apparent rotation of the disc-like organs which surround their mouths and are covered with _cilia_, or little hairs. They are minute creatures, and can best be viewed with a microscope, although the larger forms may be seen without such assistance. They are widely diffused on the surface of the earth, inhabit lakes as well as the ocean, and are found in cold, temperate, and tropical climates. The rotifera were once supposed to be hermaphrodites, but the existence of sexes in one species has been clearly established. The male, however, is much smaller, and far less developed than the female. In some of these species, germ-cells, or eggs, are found, which do not require fecundation for reproduction or development, so that they belong to the non-sexual class.
The third variety of hermaphrodites embraces those animals in which the male organs are so disposed as not to fecundate the ova of the same body, but require the co-operation of two individuals, notwithstanding the co-existence in each of the organs of both sexes. Each in turn impregnates the other. The common leech, earth-worm, and snail, propagate in this manner.
_Unnatural hermaphrodism_ is characteristic of insects and crustaceans, in which the whole body indicates a neutral character, tending to exhibit the peculiarities of male or female, in proportion to the kind of sexual organs which predominates. Half of the body may be occupied by male, the other half by female organs, and each half reflects its peculiar sexual characteristics. Some butterflies are dimidiate hermaphrodites; _i.e._ one side of the body has the form and color of the male, the other the form and color of the female. The wings show by their color and appearance these sexual distinctions. The stag-beetle is also an example. We have accounts of dimidiate hermaphrodite lobster, male in one half and female in the other half of the body.
Among the numerous classes of higher animals, which have red blood, we have heard of no well-authenticated instance of hermaphrodism, or the complete union of _all_ the reproductive organs in one individual. True, the term _hermaphrodite_ is often applied to certain persons in whom there is some malformation, deficiency, or excess, of the genital organs. These congenital deformities consisting of combined increase or deficiency, supernumerary organs, or transposition of them, which usually render generation physically impossible, have been called _bisexual hermaphrodism_ and classed as monstrosities. We have many published accounts of them, hence, further reference to them here is unnecessary. We would especially refer those readers who may desire to make themselves further acquainted with this interesting subject, to the standard physiological works of Flint, Foster, Carpenter, Bennett, Dalton, and others equally eminent in this particular branch of science.
Certain theories have been advanced concerning conditions which may influence the sex of the offspring. One is that the right ovary furnishes the germs for males, the left for females that the right testicle furnishes sperm capable of fecundating the germs of males, and the left testicle, the germs of the left ovary, for females. That fecundation sometimes takes place from right to left and thus produces these abnormal variations. We merely state the hypothesis, but do not regard it as accounting for the distinction of sex, or as causing monstrosities, though it is somewhat plausible as a theory, and is not easily disproved. In the lower order of animals, as sheep and swine, one of the testicles has been removed, and there resulted afterward both male and female progeny, so that the theory seems to lack facts for a foundation.
We sometimes witness in the child excessive development, as five fingers, a large cranium, which results in dropsical effusion, or deficient brain, as in idiots; sometimes a hand or arm is lacking, or possibly there is a dual connection, as in the case of the Siamese twins; or, two heads united on one body. It is difficult to give any satisfactory explanation of these abnormal developments. From age to age, the type is _constant_, and preserves a race-unity. The crossings of the races are only transient deviations, not capable of perpetuation, and quickly return again to the original stock. This force is persistent, for inasmuch as the individual represents the race, so does his offspring represent the parental characteristics, in tastes, proclivities, and morals, as well as in organic resemblances. This constancy is unaccountable, and more mysterious than the occasional malformation of germs in the early period of foetal life. If to every deviation from that original form and structure, which gives character to the productions of nature, we apply the term _monster_, we shall find but very few, and from this whole class there will be a very small number indeed of _sexual_ malformations. If the sexes be deprived of the generative organs, they approach each other in disposition and appearance. All those who are partly male and partly female in their organization, unite, to a certain extent, the characteristics of both sexes. When the female loses her prolific powers, many of her sexual peculiarities and attractions wane.
DIOECIOUS REPRODUCTION.
_Dioecious_ is a word derived from the Greek, and signifies _two households;_ hence, _dioecious reproduction_ is sexual generation by male and female individuals. Each is distinguished by sexual characteristics. The male sexual organs are complete in one individual, and all the female organs belong to a separate feminine organization. In some of the vertebrates, impregnation does not require sexual congress; in other words, fecundation may take place _externally_. The female fish of some species first deposits her ova, and afterwards the male swims to that locality and fertilizes them with sperm.
In higher orders of animals, fecundation occurs _internally_, the conjunction of the sperm and germ cells requiring the conjugation of the male and female sexual organs. The sperm-cells of the male furnish the quickening principle, which sets in play all the generative energies, while the germ-cell, susceptible to its vivifying presence, responds with all the conditions necessary to evolution. The special laboratory which furnishes spermatic material is the _testes_, while the stroma of the _ovaries_ contributes the germ-cell. Several different modes of reproducing are observed when fecundation occurs within the body, which vary according to the peculiarities and organization of the female.
MODES OF DIOECIOUS REPRODUCTION.--A very familiar illustration of one mode is found in the common domestic fowl, the egg of which vivified within the ovarium, is afterward expelled and hatched by the simple agency of warmth. This mode of reproduction is called _oviparous generation_.
The ovaries, as well as all their latent germs, are _remarkably_ influenced by the first fecundation. It seems to indicate monogamy as the rule of higher sexual reproduction. The farmer understands that if he wishes to materially improve his cows, the first offspring must be begotten by a better, purer breed, and all that follow will be essentially benefited, even if not so well sired. Neither will the best blood exhibit its most desirable qualities in the calves whose mothers have previously carried inferior stock. So that there are sexual ante-natal influences which may deteriorate the quality of the progeny.
The Jews understood this principle, in the raising up of sons and daughters unto a deceased brother. The fact that the sexual influence of a previous conception is not lost, is illustrated when, in a second marriage, the wife bears a son or daughter resembling bodily or mentally, or in both of these respects the former husband. This indicates a union for life by natural influences which never die out.
With some species of fish and reptiles, the egg is impregnated internally, and the process of _laying_ commences immediately, but it proceeds so slowly through the excretory passages, that it is hatched and born alive. This is called _ovo-viviparous generation_.
As we rise in the scale of organization, animals are more completely developed, and greater economy is displayed in their preservation. The germ passes from the ovary into an organ prepared for its reception and growth, to which, after fecundation, it becomes attached, and where it remains until sufficiently developed to maintain respiratory life. This organ is called the _womb_, or _uterus_, and is peculiar to most mammalia. This mode of reproduction is termed _viviparous generation_.
The kangaroo and oppossum are provided with a pouch attached to the abdomen, which receives the young born at an early stage of development.
They remain in contact with the mammae, from which they obtain their nourishment, until their growth is sufficiently completed to maintain an independent existence. This is called _marsupial generation_. The variety of reproduction which is most interesting, is that of the human species, and is called _viviparous generation_. It includes the functions of copulation, fecundation, gestation, parturition, and lactation.
For the full and perfect development of mankind, both mental and physical chastity is necessary. The health demands abstinence from unlawful intercourse. Therefore children should not be allowed to read impure works of fiction, which tend to inflame the mind and excite the passions. Only in total abstinence from illicit pleasures is there moral safety and health, while integrity, peace, and happiness, are the conscious rewards of virtue. Impurity travels downward with intemperance, obscenity, and corrupting diseases, to degradation and death. A dissolute, licentious, free-and-easy life is filled with the dregs of human suffering, iniquity, and despair. The penalties which follow a violation of the law of chastity are found to be severe and swiftly retributive.
[Illustration: Fig. 100.
Male]
[Illustration: Fig. 101.
Female]
[Illustration: Fig. 102.
Outline of the Female Urinary and Generative Organs.]
The union of the sexes in holy matrimony is a law of nature finding sanction in both morals and legislation. Even some of the lower animals unite in this union for life, and instinctively observe the law of conjugal fidelity with a consistency which might put to blush other animals more highly endowed. It is important to discuss this subject and understand our social evils, as well as the unnatural desires of the sexes, which must be controlled or they lead to ruin. Sexual propensities are possessed by all, and they must be held in abeyance, until they are exercised for legitimate purposes. Hence parents ought to understand the value of mental and physical labor to elevate and strengthen the intellectual and moral faculties of their children, to develop the muscular system and direct the energies of the blood into healthful channels. Vigorous employment of mind and body engrosses the vital energies and diverts them from undue excitement of the sexual desires.
[Illustration: Fig. 103.
Outline of the Male Reproductive Organs.]
Sexual generation by pairing individuals is the most economical mode of propagating the species. The lower orders of animals possess wonderful multiplicative powers and their faculty for reproduction is offset by various destructive forces. The increased ability for self-maintenance implies diminished reproductive energy; hence the necessity for greater economy and safety in rearing the young. As certain larvae and insects increase, the birds which feed upon them become more numerous. When this means of support becomes inadequate, these same birds diminish in number in proportion to the scarcity of their food. Many have remarked that very prolific seasons are followed by unusual mortality, just as periods of uncommon prosperity precede those of severe disaster.
The increased mental and moral cultivation of mankind imposes upon them the necessity for greater physical culture. "Wiser and weaker," is a trite saying, and means that the exercise of the higher nature discloses the equivalent necessity of culturing the body, in order to support the increasing expenditures of the former. Mental and moral discipline are essential for a proper understanding how to provide for the body, for physical training increases the capacity of the individual for self-preservation. Constant vigilance is the price of health as well as of liberty.
It is an interesting physiological fact that, while the growth and development of the individual are rapidly progressing, the reproductive powers remain almost inactive, and that the commencement of reproduction not only indicates an arrest of growth, but, in a great measure, contributes toward it. From infancy to puberty, the body and its individual organs, structurally as well as functionally, are in a state of gradual and progressive evolution. Men and women generally increase in stature until the twenty-fifth year, and it is safe to assume that perfection of function is not established until maturity of bodily development is completed. Solidity and strength are represented in the organization of the male, grace, and beauty in that of the female. His broad shoulders represent physical power and the right of dominion, while her bosom is the symbol of love and nutrition. The father encounters hardships, struggles against difficulties, and braves dangers to provide for his household; the mother tenderly supplies the infant's wants, finding relief and pleasure in imparting nourishment, and surrounds helpless infancy with an affection which is unwearied in its countless ministering attentions. Her maternal functions are indicated by greater breadth of the hips. Physical differences so influence their mental natures, that, "before experience has opened their eyes, the dreams of the young man and maiden differ." The development of either is in close sympathy with their organs of reproduction. Any defect of the latter impairs our fair ideal, and detracts from those qualities which impart excellence, and crown the character with perfections. Plainly has Nature marked out, in the organization, very different offices to be performed by the sexes, and has made these distinctions fundamental.
Likewise, Nature expresses the intention of reproduction by giving to plants and animals distinctive organs for this purpose. These are endowed with exquisite sensibility, so that their proper exercise produces enjoyment beneficial to both. Excessive sexual indulgence not only prostrates the nervous system, enfeebles the body, and drains the blood of its vivifying elements, but is inconsistent with intellectual activity, morality, and spiritual development. The most entrancing delights and consummate enjoyments are of the emotive order, ideal, abstract, and pure, so inspiring that they overpower the grosser sensual pleasures and diffuse their own sweet chastity and refining influence over all the processes of life.
Hence, the gratification of the sexual instincts should always be moderate. It should be regulated by the judgment and will, and kept within the bounds of health. No person has a moral right to carry this indulgence so far as to produce injurious consequences to either party, and he who cannot refrain from it is in no proper condition to propagate his species. In all culture there must be self-control, and the practice of self-denial at the command of love and justice is always a virtue.
Self-government is the polity of our people, and we point with pride and laudable exultation to our political maxims, laws, and free institutions. The family is the prototype of society. If self-restraint be practiced in the marital relation, then the principle of self-control will carry health, strength, and morality into all parts of the commonwealth. The leading characteristics of any nation are but the reflection of the traits of its individual members, and thus the family truly typifies the practical morality and enduring character of a people.
OVULATION.
The _Ovaries_ are those essential parts of the generative system of the human female in which the ova are matured. There are two ovaries, one on each side of the uterus, and connected with it by the Fallopian tubes; they are ovoidal bodies about an inch in diameter, and furnish the _germs_ or ovules. These latter are very minute, seldom measuring 1/120 of an inch in diameter, and frequently are not more than half that size.
The ovaries develop with the growth of the female, so that, finally, at the pubescent period, they ripen and liberate an ovum, or germ vesicle, which is carried into the uterine cavity through the Fallopian tubes.
With the aid of the microscope, we find that these ova are composed of granular substance, in which is found a miniature yolk surrounded by a transparent membrane, called the _zona pellucida_. This yolk contains a germinal vesicle in which can be discovered a nucleus, called the _germinal spot_. The process of the growth of the ovaries is very gradual, and their function of ripening and discharging an ovum every month into the Fallopian tubes and uterus is not developed until between the twelfth and fifteenth years.
This period, which indicates, by the feelings and ideas, the desires and will, that the subjects are capable of procreation, is called _puberty_.
The mind acquires new and more delicate perceptions, the person becomes plumper, the mammae enlarge, and there is grace and perfection in every movement, a conscious completeness for those relations of life for which this function prepares them. The period of puberty is also indicated by
MENSTRUATION.
The catamenial discharge naturally follows the ripening and liberation of an ovum, and as the ovaries furnish one of these each month, this monthly flow is termed the _menses_ (the plural of the Latin word _mensis_, which signifies a month). The menstrual flow continues from three to five days, and is merely the exudation of ordinary venous blood through the mucous lining of the cavity of the uterus. At this time, the nervous system of females is much more sensitive, and from the fact that there is greater aptitude to conception immediately before and after this period, it is supposed that the sexual feeling is then the strongest. When impregnation occurs immediately before the appearance of the menses, their duration is generally shortened, but not sufficiently to establish the suspicion that conception has taken place. The germ is the contribution of the female, which provides the conditions which only require the vivifying principle of the sperm for the development of another being. The period of aptitude for conception terminates at the time both ovulation and menstruation cease, which, unless brought about earlier by disease, usually occurs about the forty-fifth year of her age.
FECUNDATION.
Since in the beginning God created male and female, and said unto them, "Be fruitful, and multiply, and replenish the earth," it is evident that what was originated by creation must be continued by procreation. The process of generation the reader will find described on pages 12 and 13.