The Biology, Physiology and Sociology of Reproduction

The casual observer, even if he watches thoughtfully the various activities of plants and animals, would hardly believe these activities capable of classification into two general classes. He notes the germination of the plant seed and its early growth, step by step approaching a stage of maturity; it blossoms, produces seed, and if it is an annual plant, withers and dies. If it is a perennial plant its leaves only, wither and die at the approach of winter, the plant passing into a resting stage from which it awakes the following spring to repeat again its annual cycle.

If he observes an animal he finds that it similarly develops to a stage of maturity, reproduces its kind, withers and dies; but incident to these general activities he notes numerous others that seem to have no relation to the activity of the plant. He sees men tilling the fields, felling the forests, building houses, factories and railroads; he sees them build hospitals, colleges and churches. Is it possible to group all of these activities of plants and animals into two general groups? A more critical view of these activities makes it evident that they are all directed either to the maintenance and protection of the individual, or the maintenance and protection of the race. Those directed towards the maintenance of self are called egoistic activities, while those directed to the maintenance of the race are called phyletic activities.

The Egoistic Activities.

The term egoistic implies that the effort is directed towards the ego or self, and includes all of those activities directed to the support, protection, defense and development of oneself. As illustrated in the plant organism, the taking of nourishment from the air and soil, the development of the stem, branches, roots and leaves, are egoistic activities. In the animal-we may take, for example, man-the egoistic activities begin with the drawing of nourishment from the mother's breast and include all those activities of early childhood usually called play, the real significance of which is to develop the neuro-muscular system and the special senses, to that condition of alertness and strength that will make the growing individual self-supporting. A very large part of the activities of the self-supporting human subject are directed towards the earning of his daily bread, and of clothing and shelter. The activities of the school and college period, devoted, as they are, almost exclusively to the development of the youth's powers, intellectual or physical, are also egoistic. Even the pursuit of pleasure and of sense gratification on the part of the individual belongs to this same group of activities.

The Phyletic Activities.

As the etymology of the term suggests, these activities are devoted to the propagation, maintenance and protection of the race.

a. Reproduction.-The most fundamental one of the activities for the maintenance of the race is reproduction. Every living organism, whether plant or animal, possesses the power to reproduce its kind. Some plants produce spores and some produce seeds. Reference was made above to the production of the flower in plants. The flower represents the reproductive organ of the plant, and the real object of the flower is to produce the seed. Animals produce eggs from which the young develop, either through a process of incubation outside of a maternal body or an analogous process within the maternal body. In the latter case the young are brought forth as living organisms.

b. Support and Protection of Offspring.-Whether we consider the plant seed, or the animal egg or newborn-in any case the parental organism must provide for the support and protection of the offspring during those stages of development when it is unable to support and protect itself.

The plant deposits in or about the seed a supply of nourishment sufficient to support it during the germinating process and until it is able to gain its own support from the soil and air. Furthermore, the plant protects the seed by means of the various seed envelopes, against the cold and moisture of winter.

In a similar way the young animal is supplied by its parents with nourishment. The young bird is incubated within the egg where a supply of nourishment is provided sufficient to develop the bones, muscles, nervous system, blood, glands and covering-all developed to a point that makes the bird able to take from the mother during the early weeks after its release from the shell, such nourishment as the mother may provide. In the meantime it must be brooded and protected in the parental nest until it is able to provide for its own protection. Similarly the young mammal is developed within the body of the maternal organism to a point where it is able to perform the primitive functions of life. For weeks, months or even years, according to the class of the animal, it must be supported and protected by its parents. The human young receives milk from its mother's breast and protection in its mother's arms during its first year, after which it continues to receive nourishment, clothing and protection under the parental roof for a period varying from eighteen to twenty years, or even longer.

c. Support and Protection of Weaker Members of Society.-Young animals are supported and protected because they are unable to support and protect themselves. If they were not thus cared for the race would become extinct. Now, there are certain individuals, orphans for example, who have, through some accident, been deprived of their natural support and protection. If these weaker members of society, not yet able to support and protect themselves, were not provided for, they would perish and become thus lost to the race. From the time of primeval man to the present, these weaker individuals of society who have been deprived of their natural protectors, have been cared for by the stronger members of society and afforded such support and protection as they may need to make them independent. In a similar way the sick and defective members of society are cared for by the strong. Thus we see that the building and maintenance of orphanages, hospitals, asylums and "homes," are activities that belong clearly to the group of phyletic or altruistic activities.

General Changes in the Body.

a. Pilosity.-The human being belongs to the vertebrate class, mammalia, and as a member of that class he possesses over the cutaneous surface of the body, excepting the palms of the hands and soles of the feet, hair follicles which produce the hairy covering typical of mammals. A careful study of the distribution of the hair on the surface of the human body, comparing it with that of the anthropoid apes, demonstrates that the distribution is identical; and the "lay" of the hair in any one region of the human body corresponds exactly with that of the same region in the ape. For example-the hair on the forearm points outward and upward; on the upper arm down-ward and outward and so on throughout in the human and simian types. Every child comes into the world with a coat of rudimentary hair which is shed at once. Aside from the growth of hair on the head, including the brows and the lashes, the skin is quite free from any noticeable growth of hair for months or even years. Beginning at the age of puberty, however, the growth of hair is very much accelerated over the whole pilous surface of the body, particularly upon the face, in the axilla and over the pubic region. It is a generally recognized law of biology, that, at the period of sexual development, the hairy mammalian character becomes accentuated. The increase in the growth of hair at this time can have only one interpretation, viz., that the ancestors of man represented a very much higher degree of pilosity than is the case with man at the present time. It is interesting to note in this connection the almost universal attempt of men to rid the face of this hairy growth by various devices, either pulling the beard or shaving it. The origin of this custom of depilation probably dates back to the remote past and has been observed as a custom among both savages and civilized peoples.

b. The Voice.-In all animals the voice plays an important part in sexual and social relations. In many animals the voice seems to have almost no other function than as a sex call, or a communication between mates and between parents and young. The human subject illustrates this general biological principle in the profound changes which the voice undergoes at the time of puberty. These changes in the male subject consist in increasing the depth of the larynx, thereby increasing the length of the vocal cords which in turn modifies the pitch of the voice, usually about an octave, making it not only lower but much more pleasing in quality and greatly increased in volume.

c. Bone, Muscle and Gland.-Of incalculably greater importance than the changes described above though perhaps less noticeable to the casual observer, are those physical changes which the body undergoes during the first half of the period of adolescence. I refer to the growth of bone, of muscles and of those internal organs associated with nutrition.

The first step in these profound physical changes is a rapid growth in height that makes itself manifest about the fifteenth year. It is not at all unusual for a boy to grow from four to six inches in a year. This increase in height is very largely due to a lengthening of the thigh and leg bones. In serial homology with the thigh and leg are the bones of the arm and we find that these are undergoing an increase in length commensurate with the increase of the legs. So the boy outgrows his clothes; his coat sleeves are drawn up half way to his elbows and his trousers half way to his knees. The muscles scarcely keep pace with the bones in their growth, and tend to be flabby and to lack usual tonicity. It is difficult for the youth to hold his back straight and his shoulders back; he is awkward and ungainly in his movements and becomes easily fatigued because of the condition of his muscles. But the muscles follow immediately in their development and rapidly gain volume and tonicity, filling out the arms, legs, back and shoulders with large masses of firm muscular tissue. The growth of these muscle masses changes the dimensions of the youth and he fills out in his girths as rapidly as, in the previous period, he increased in length measurements.

All of this increase in bulk can only be accomplished by increased activity of all the nutritive processes. The appetite is practically insatiable; the boy can eat three square meals in the day and lunches between meals. If he wakes up in the night he is hungry. To accomplish the digestion and absorption of this food material, the alimentary tract throughout, and particularly the stomach is greatly increased in size. To accomplish the distribution of the food (blood) the heart also is increased in size and strength. With increased bulk of muscle and increased quantity of food we have increased oxidation in the tissues. This requires increased respiration, which demand is satisfied by rapid development of the respiratory system. The thorax increases in dimensions in all directions; it becomes deeper, broader and longer. Not only does the thorax become more capacious but also more mobile and more responsive to the varying requirements of the system.

If we are interested in the biology of all these changes, we need not go far to discover the natural causes at work to produce them. Nature is preparing in the youth a home builder; it is preparing an individual who can support and protect not only himself, but also a family. This equipment in the case of primitive man must necessarily be one of bone and brawn. While under the conditions of modern society the necessity for bone and brawn is somewhat less marked, the plan of nature is no less evident and no less interesting.

The Genital System.

a. Structural Changes.-The external genitals, besides showing the pudendal pilosity referred to above, are all greatly increased in size. The penis is increased in all of its dimensions, the testes become very much increased in size, the scrotum, probably because of the increased weight of the testes, is also lengthened.

b. Functional Changes.-The testes and associated glandular bodies gradually develop the power of forming perfect semen, capable of fertilizing the human ovum. When these organs thus become capable of procreation, the period of puberty is complete.

In this connection it is important to note that the development of the testes produces a profound effect upon both the physical and mental characteristics of the young man. This effect is produced through a substance formed in the testes and reabsorbed into the body, thus gaining access to the blood where it exerts its mysterious but profound influence. Just how this affects the mind and body will be discussed in detail in a subsequent chapter.

The external genitals of the human male consist of the penis and scrotum, the latter containing the testes.

The penis of the young man who has completed the stage of puberty consists (1) of the two corpora cavernosa, as they are called, or erectile bodies, called cavernosa because they contain numerous blood sinuses which when filled cause the organ to erect. (2) Between and beneath the corpora cavernosa lies the corpus spongiosum which consists principally of the urethra. Around these three cylindrical bodies there is a sheath of loose connective tissue, outside of which is the skin.

About one inch of the distal end of the organ is differentiated into a sort of head which is called the glans over which, in the young child, the skin is redoubled and called the prepuce or foreskin. The glans is covered and the prepuce is lined by mucous membrane. Over the glans the mucous membrane is red, thin and moist and possesses numerous nerve papill?. The prepuce, as stated above, usually covers the glans penis in young children and may do so throughout life. It is sometimes adherent to the glans. This is abnormal, and as soon as it is discovered the adhesions should be broken up by a physician. The normal prepuce of the adolescent male should be free from the glans and should be sufficiently loose easily to retract back of the glans, a position it is likely to take in erection. If the prepuce extends half an inch or more beyond the glans penis as a little flap of skin, or if it is constricted at the opening so that it is difficult to clear the glans or to replace the prepuce when it is once back of the glans, the condition is not normal, and should have the attention of a competent surgeon.

One can easily understand the need of a prepuce in the case of primeval man, who was practically unprotected by clothing, but in the present condition of civilized races the prepuce is certainly an unnecessary appendage, and there are several good reasons why the prepuce should be removed. This operation [circumcision] is not, in any sense, to be looked upon as a mutilation, but simply a hygienic measure made advisable, if not necessary, by the unnatural conditions under which we are now existing.

Beneath the prepuce cheesy secretions from the glands back of the head of the penis collect, and if the organ is not frequently cleansed these accumulated secretions may serve as an irritant. Such local irritation is one of the most prevalent causes of masturbation in boys.

The removal of the prepuce in young children is an exceedingly simple operation and not by any means difficult or dangerous in the adult. If the prepuce is removed the organ will need no especial care, as contact with the clothing will remove the secretions as they appear. Furthermore, the glans penis becomes less sensitive and therefore less subject to local irritation thus simplifying the young man's problems in sexual hygiene.

The penis in its flaccid state varies considerably in size, due not only to varying conditions of temperature but also to individual peculiarities. The organ may vary between 2? inches and 6 inches in length in the flaccid state and between 5 inches and 8 inches in the erected condition. The size of the generative organs is not an index of virility in the male.

The testes are the male generative glands and are described as about 1? inches in length, 1? inches in width and nearly 1 inch in thickness. The testes are contained within the scrotal sac, the outside coat of which is a thin wrinkled skin, within which are four thin coats. Next to the testes and enveloping the spermatic cord is a thin covering which is carried down into the scrotum when the testicle leaves the abdomen, where it is formed. This descent of the testes from the abdomen takes place normally in the later weeks of intrauterine life. The testes may, however, through some unusual condition, be retained and make their descent months or even years later. If the testes have not descended by the end of the age of puberty, the advice of a competent surgeon should be sought.

SEMEN

TESTICULAR CONTRIBUTION. SPERMATOZOA

SEMINAL GRANULES

MUCIN AND WATER

VESICULAR CONTRIBUTION.

(In quantity greater than all the rest.) ALBUMIN

ALKALINE SALTS

WATER

PROSTATIC CONTRIBUTION.

(Viscid and opalescent.) PROTEINS

ALKALINE SALTS

WATER

Plate II

Male Sexual Apparatus

The outer coat of the testis is called the tunica albuginea. [See Plate 2.] This tunic or coat sends fibrous partitions into the testis which divide the organ into lobules, each one being conical in shape with the apex directed towards the epididymis, which is that mass of blood vessels and tissues which one can feel on one side of each testis. Within these lobules the spermatozoa are formed by a complex process of cell division and cell germination upon whose description we need not enter here.

The spermatozoon may be described as the male sexual cell whose function is to fertilize the female ovum. The spermatozoon is about 1/20 of an inch in length and consists of a head, body and a vibratile tail. In the human spermatozoon the head is ovoid, appearing pear-shaped or pointed in one view and elliptical in another.

The epididymis referred to above, consists of a mass of coiled tubes and blood vessels. After the secretion passes through the tortuous coils of ciliated tubes of the epididymis, it is collected into a single tube called the vas deferens, which passes as a part of the spermatic cord from the scrotum, up through the groin and over the pubic arch into the pelvic cavity, passing down back of the bladder where it is slightly dilated into an ampulla, beyond which the duct is again contracted into a narrow tube, and the two ducts, one from either side, converge and pass into the prostate gland, where they empty into the urethra.

The seminal vesicles.-The seminal vesicles are small bladder-like organs supposed originally to contain the secreted semen collected from the testes. There are two of these vesicles, from each a small duct joins the vas deferens making up what is known as the ejaculatory duct. The two ejaculatory ducts coming together in the prostate gland open into the urethra. The seminal vesicles possess glandular walls and secrete the substance which they contain, no part of the secretion of the testes normally finding its way into the vesicles.

The prostate gland, a portion of which is homologous with the female uterus and called uterus masculinus, is situated around the neck of the bladder and is traversed not only by the urethra (prostatic portion), but also by the ejaculatory ducts. There are numerous gland ducts which-collecting the secretion of the prostate gland-open into the urethra in the prostatic portion.

Just beyond the prostate are two small glands called Cowper's Glands whose ducts enter the urethra some distance beyond the prostate, at the root of the penis.