Part 2 (1/2)
Vegetable Husbands.--Within the cup formed by the calyx and corolla are placed the _stamens_ and _pistils_ of 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 the _anther_, which contain a fine, microscopic dust, the _pollen_, 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, Linnaeus, whose name was immortalized by his careful study and cla.s.sification of organized life, made the number of stamens possessed by various flowers the basis of a systematic cla.s.sification.
For example, a flower having but one stamen was cla.s.sed as _monandria_, which means, literally, one husband; one having two stamens was cla.s.sified as _diandria_; flowers having a large number of male organs were termed _polyandria_, or many husbands.
The Female Organ of Flowers.--The _pistil_ occupies the very center of the flower. It produces and contains in a cell, the female element, termed the _ovule_. It is surmounted by the _style_ and the _stigma_.
A series of plants in which the s.e.xual organs are not visible to the eye are termed _cryptogamia_, which means literally, hidden marriages.
As we proceed to study the anatomy of the human s.e.xual apparatus we shall be constantly struck with the remarkable correspondence between animals and vegetables in the structure and functions of the s.e.xual apparatus.
s.e.xual Organs of Animals.--The male reproductive element is called a _spermatozoon_ or _zoosperm_. The female element is called an _ovum_, literally, an egg.
The Spermatozoon.--The male reproductive element of animals is formed by an organ called the _testis_, or _t.e.s.t.i.c.l.e_, 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 pa.s.s 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 t.e.s.t.i.c.l.e down into the s.c.r.o.t.u.m, either completely or partially.
In a few animals, as in the porcupine, the opening is never fully closed, and the testis remains in the cavity of the body most of the time, pa.s.sing 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 pa.s.sage 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 t.e.s.t.i.c.l.e 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 t.e.s.t.i.c.l.es are connected with the urinary pa.s.sage 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 at further length upon the structure of the t.e.s.t.i.c.l.es, 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 zoosperms.
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 spermatozoon 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 p.u.b.erty to old age, though at the two extremes of existence they are imperfectly developed. When not discharged 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 a.s.serted 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 zoosperms 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, const.i.tutes the _s.e.m.e.n_.
The Ovum.--The female element of generation, the ovum, is produced by an organ called the _ovary_, of which there are two in each individual.
In size and form, the ovary closely resembles the t.e.s.t.i.c.l.e. Like the latter organ, also, it is formed within the body early in the process of development; but instead of pa.s.sing outward and downward, as does the t.e.s.t.i.c.l.e, 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 zoosperms. As a general rule, in the human female, a single ovum is developed and discharged once in about four weeks, during the period of s.e.xual activity.
Fecundation.--It is often asked, and the question has elicited some discussion, Which is the princ.i.p.al reproductive element; the zoosperm, 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 preeminence; 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 as _fecundation_. 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, Linnaeus, 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 const.i.tutes the curtains; the anthers are the testes; the pollen, the fecundating fluid; the stigma of the pistil, the external genital aperture; the style, the v.a.g.i.n.a, 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 a.n.a.logy 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 sc.u.m 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 in contact 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 the _arum_ of 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.