Sexual reproduction

“ Sexual reproduction is quite a distinct matter. Here, in all these cases, what is required is the detachment of two portions of the parental organisms, which portions we know as the egg or the spermatozoon. In plants it is the ovule [395] and the pollen-grain, as in the flowering plants, or the ovule and the antherozooid, as in the flowerless. Among all forms of animal life, the spermatozoa proceed from the male sex, and the egg is the product of the female. ”

“ CHAPTER IVToC THE SEXUAL APPETITE
If we sum up the three preceding chapters we arrive at the philosophical conclusion that reproduction depends on the general natural tendency of all living beings to multiply indefinitely. Fission and sexual reproduction arise from the simple fact that the growth of each individual is necessarily limited in space as well as time. Reproduction is thus destined to assure the continuation of life; the individual dies but is perpetuated in his progeny. We do not know why the crossing of individuals is rendered necessary by the phenomenon of conjugation. ”

“ Thus we have shown the easy gradation, and therefore the probable derivation, of the highest mode of sexual reproduction—the unisexual—from the ordinary processes of growth, through the different grades of asexual and bisexual reproduction. The derivation of different modes of sexual reproduction from each other will not, I think, be questioned. Still clearer is the fact that non-sexual reproduction is but a modification of the ordinary process of growth. The only place where there is any gap is between the asexual and the sexual modes. ”

“ How should we have imagined the possibility of fertilization for successive generations, of hermaphroditism, or of reproduction by fissure, etc., being found among the methods which Nature adopts for replenishing the earth, had we contented ourselves with an examination of the comparatively simple methods of ordinary sexual reproduction? ”

“ What other reason can there be why the circuitous process of sexual reproduction has been preferred? It may be said that the arrangement by which multiplication is secured through special germ-cells, more or less apart from the cells which build up the body, may be justified as an arrangement which prevents or tends to prevent the transmission of bodily modifications, many of which are detrimental. ”

“ Without the Ovaries there would be no ova or eggs, and without the ova there would be possible no reproductive purposes, and therefore no office for the sex organs at all, for reproduction is the fundamental office, function, and purpose of the entire sexual organism. ”

“ Sexual reproduction does not essentially differ, as we have seen, from budding or self-division, and these processes graduate through the repair of injuries into ordinary development and growth; it might therefore be expected that every character would be as regularly transmitted by all the methods of reproduction as by continued growth. ”

“ Having once originated, the sexual type of reproduction possessed a definite survival value which assured its continuation. Sex makes possible a crossing of strains, which evidently possesses some great advantage, since the few simple forms which have no such division of reproductive functions have undergone no great development and all the higher, more complicated animals are sexual. ”

“ From these simplest forms of sexual propagation, as we can observe them to-day in the lowest Zoophytes, the Gastræads, Sponges, and Polyps, we gather most important data. In the first place, we learn that, properly speaking, nothing is required for sexual reproduction except the fusion or coalescence of two different cells—a female ovum and male sperm-cell. All other features, and all the very complex phenomena that accompany the sexual act in the higher animals, are of a subordinate and secondary character, and are later additions to this simple, primary process of copulation and fecundation. ”

“ But when I maintain that the meaning of sexual reproduction is to render possible the transformation of the higher organisms by means of natural selection, such a statement is not equivalent to the assertion that sexual reproduction originally came into existence in order to achieve this end. The effects which are now produced by sexual reproduction did not constitute the causes which led to its first appearance. Sexual reproduction came into existence before it could lead to hereditary individual variability. ”

“ II. That sex is determined in the moment of fertilization by the reciprocal interaction of male and female, of zoösperm and ovum. One variant of this theory maintains that each reproductive element strives for the reproduction of its own sex; that a struggle takes place and that the victor in the contest stamps its own sex-likeness upon the fertilized product. ”

“ The lower forms of animal and plant life often reproduce themselves without the aid of sex, and it has even been argued that reproduction and sex are directly antagonistic, that active propagation is always checked when sexual differentiation is established. "The impression one gains of sexuality," remarks Professor Coulter, foremost of American botanists, "is that it represents reproduction under peculiar difficulties." ”

“ The offspring will thus be the result of the unfolding of a bit of germ plasm which will be different from that from which either of its parents developed, and these differences will result in congenital variations. Sexual reproduction thus results in congenital variations; and if congenital variations are necessary for the evolution of the living machine—and we shall soon see reason for believing that they are—we find that sexual reproduction is a device adopted for bringing out such congenital variations. ”

“ The best equipped males will thus crowd out the less well-equipped in the matter of reproduction, and thus the relevant characters will be increased and perfected through sexual selection. It is, of course, a necessary assumption that these secondary sexual characters may be transmitted to the female, although perhaps in rudimentary form. ”

“ Success in the attainment of reproduction depends upon the successful discharge of the sexual function; and the discharge of the sexual function depends primarily upon an individual of one sex coming into contact with one of the opposite sex at the appropriate season and when its appropriate organic condition arises. ”

“ 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 [pg 203] 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. ”

“ Nature calls upon the male animal to make a contribution for procreation, which contribution is, always has been, and, in the very nature of the case, always must be a certain tax upon the powers of the male animal. When the intercourse is indulged for procreation only, the male animal can well afford to make the contribution. Even with that, the contribution which the male makes to procreation is incomparably less depleting for him than are the contributions which the female makes for her.
11. Will vital fluid flow with every sexual intercourse? ”

“ The physiology and pathology of the menacme coincides with the normal processes and pathological changes respectively of the female genital organs consequent on their functional activity as organs of sexual sensation and of reproduction. Woman as wife and mother stands at the climax of her existence.
In a quite astonishing manner, however, many of the advocates of the modern movement for the emancipation of women contest the significance of maternity to women. ”

“ 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, the penis in the male and the vagina in 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. ”

“ We can only say it appears probable that there exist several causes of the determination of sex the co-operative action of which proves effectual. Not in the ovum alone, nor in the spermatozoon alone, but in the reciprocal influence they exert one upon the other in the act of conception is sex determined. In the latter connection the relative and absolute ages of the progenitors appear to have a certain influence in the determination of the sex of the embryo; of importance also is the greater or less demand made upon the sexual capacity of the begetter ”

“ Passing to innate variations—variations, that is to say, which are the outcome of normal development from the fertilized ovum—must they be inherited, at any rate, in some degree? It seems to me that they must, on the hypothesis that sexual generation involves simply the blending or commingling of the characters handed on in the ovum or the sperm. ”

“ Every individual among the higher animals, whether male or female, begins as an impregnated ovum in the mother's body. Any such ovum contains elements of constitution from both of its parents. In the earliest existence of this impregnated ovum, there is a season of sexual indifference, or indecision, in which the embryo is both male and female, having the characteristic rudiments of each sex, only indifferently manifested. ”

“ And until they are satisfied, by meeting the male and procuring from him the vitalizing fluid which will fertilize their infertile ovum; or, failing in this, until the ovum passes away from them, out of the womb, they know no rest. At such times they will run all risks, incur all sorts of danger, do every possible thing to secure pregnancy. The thousand-and-one ways which female animals use to make known to their male mates their sexual desire and needs, when in heat, is a most interesting and wonderful story, a record made up of facts which would be well worth any student's knowing. ”

“ Moreover, in no single marriage is the reproductive capacity of the wife utilized to the full, up to the time of extinction of her generative faculty; either because the potency of the male partner undergoes a gradual decline, or, it may be, because, after a while, sexual intercourse becomes less frequent, or because precautions against procreation are taken. ”

“ The last step in generation is reached in the mammals. Here not only fertilization is accomplished within the body of the female, but also the entire development of the fertilized125 ovum is carried out in the uterus, inside the female body. Hence mammals give birth to living mature young.
In these higher animals the attraction of the sex cells has been definitely transferred to, or rather changed into, the attraction of the hosts of these cells or into the sexual instinct. ”

“ By sterility in women we understand the pathological state in which a woman who is sexually mature fails to conceive, notwithstanding frequently repeated, normal sexual intercourse throughout a considerable period of time. ”

“ Similar considerations prevail in respect of marriages in which the husband has been exhausted by earlier sexual excesses, so that he retains no more than remnants of virility, whilst his semen is of doubtful fertilizing power. ”

“ The opportunity may then be seized to draw attention to the resemblance between the little ovules in the ovary of the flower and the minute ova by means of which all animal life reproduces its kind. Proceeding further, an earnest and thorough introduction to the sanctity and responsibility, the perils and duties, of the sexual life, is urgently required by the young girl before she proceeds either to marriage or to an economically independent mode of life. ”

“ Just as the soil is suitable only at certain seasons for the reception of the seed, so also in the human race intercourse does not always take place at a time suited for the reception of the semen. To be effective, coitus must occur at the proper time.... The act of intercourse that is to lead to conception may best occur either just before or just after the menstrual flow, when, moreover, there is strong desire for the sexual embrace, and neither when the body is fasting, nor when it is full of drink and undigested food. ”

“ In the previous chapter, I have described the differences between the reproductive organs of men and women, and between those of adults and children, respectively. Man and woman are, however, distinguished one from the other, not only by differences in their reproductive organs, but by other qualities as well, some of these being bodily, others mental. Such distinctive characters are spoken of as secondary sexual characters, in contradistinction to the primary sexual characters, the reproductive organs. ”

“ In a given mating, we must take into consideration such factors as impediments to coitus, as well as those numerous agencies in the female which may interfere with the union of sperm and ovum, or with the successful implantation of the fertilized egg in the uterus, and its growth and development there till normal parturition takes place. Successful reproduction depends upon the mating of sexually sound females to equally sound males. ”

“ In a wider sense of the term, we say that a woman is sterile, when, notwithstanding prolonged and repeated sexual intercourse, in circumstances favourable to procreation, she has failed to give birth to a living and viable infant. ”

“ We know that characteristics that do ensure the species are, so to speak, more deeply rooted in the biology of a given animal than characteristics that are not absolutely necessary to the preservation of a species.
Now, in the human animal and in many other species, sexual intercourse is the basic method by which the species is continued. In this elemental instinctual activity the male deposits his sperm in the receptive female, who then, within her body, nurtures and protects it until it is ready for birth. ”