by Guy Murchie
The stomach, next in sequence, is probably the most misunderstood of organs and one of the hardest to describe, because it is constantly writhing, kneading, throbbing and changing its form, particularly when its owner is under emotional stress. Empty, the stomach hangs from the bottom of the gullet like a deflated balloon, some 16 inches from top to bottom, but when it gets a message that food is coming, it begins to squirm in anticipation. Full, it tightens into a plump kidneybean shape perhaps 10 inches high, yet undulating with waves of contraction. Its juice (mainly hydrochloric acid) is so corrosive it can dissolve zinc and would blister your palm in an instant, but the mucus lining is so impervious that virtually no food, drink or gastric juice can reach the stomach walls. Between the muscular churning of the organ as a whole and the sting of its juice (felt in heartburn when it rises into the throat), food is effectively softened up for the intestines, into which it is doled in teaspoon-size doses by the judicious opening and closing of its pylorus or back door.
Once in the small intestine, longest section of the coiled 30-foot intestinal tract, the acid-laced food is neutralized by alkaline digestive fluids from pancreas and liver, then bombarded with powerful enzymes that disintegrate the proteins into amino acids, the carbohydrates into sugary glucose, the fats into fatty acids and glycerol. This is manipulated in detail by millions of hairlike projections called villi, lining the intestinal walls like nap on a towel, which dominate the chemical and frictional work of milling, absorbing and sorting the useful nutrients so they can be quickly fed into the bloodstream, at the same time letting the waste solids drift on into the large intestine and out the rectum. This is how it happens with most omnivorous and carnivorous eaters like man, but the process is considerably modified in herbivorous animals, like the cow with her four stomachs, in the sea cucumber who cures his bellyache by literally discarding his belly before swimming away to grow another one, in the spider or the starfish who digest their food outside their bodies.
Elimination, by the way, does not absolutely require an intestine or anus, for some creatures don't live long enough to have an elimination problem (death or pupation doing the eliminating) while others merely slough off waste from their outer surfaces like bark from a tree. The anus too is apt to have a different and less unsavory connotation to animals than to people. When the sea cucumber (see illustration, page 17), who had been evacuating his indigestibles out of his mouth for a hundred million years, finally evolved a separate anus for the purpose, thereby gaining a choice as to which opening to breathe through, he chose the anus! And of course this choice may have been influenced by the parasitic little pearlfish who traditionally inhabits his rectum, using his anus for a door, and who undoubtedly feels, like so many of us, that "there's no place like home."
Once we accept the rectum as a haven, it naturally follows that we accept its produce as something less than obnoxious and, in the case of primitive animals, it can turn out to be good to eat, handy to build a house with, even sculpturally delightful. Indeed where larger creatures merely get rid of their ill-smelling dung, small ones often package or mold it into something useful, sometimes into dwellings of extraordinary beauty, like the tiny rotifer's beaded tower, into dramatic landscapes, like the glistening white guano isles of Peru or the limpid South Sea atolls of exquisitely excreted coral. All shells in fact are either secreted or excreted, the distinction not always clear, while beach wastes in general offer perhaps the most appealing of all forms of ordure: the architectural fecal pellets of mollusks that turn out such housetop shapes as tiles, double gutters and even a little oriental temple roof with its bottom edges turned upward toward the sky. But it is on the ocean floor, ultimate bowel of the deep, that excrement is most pervasive and, surprisingly, ofttimes graceful. More than once its convolutions have made me think of ancient oriental script, as if the worms who ejected them were trying to convey some sort of weird, benthic intelligence.
KIDNEYS AND SECRETIONS
The liquid side of digestion and elimination inevitably centers around the kidneys, those twin organs that are indispensable to life and have to do almost entirely with the watery two thirds of the body. Kidneys are organs that evolved when fish moved into the fresh water of rivers, where they began to need something that would pump out the excess of the strange unsalted fluid they found themselves increasingly absorbing by osmosis. By the time real freshwater fish appeared, the kidney had developed into a sensitive filtering system that not only forced the unwanted water out, but in the process absorbed and salvaged most of whatever salts and valuable minerals would otherwise have departed with it. The kidney's key unit, the nephron, in modern form is smaller than a pinhead and, under a microscope, looks like a worm with a round skull - a skull that turns out to be full of blood capillaries continuously exuding watery plasma, but, at the same time, absorbing from it vital amino acids, glucose, minerals, proteins and (as an evolutionary afterthought on moving ashore) retaining more than 98 percent of the fresh water. The small residue of course is urine, and it dribbles out of tiny, wormy tributaries which, joining together from some million nephrons in each kidney, ultimately drain into a bladder to be excreted at opportune moments.
But the main function of the kidneys is maintenance of an exact proportion of water in the blood (which they clean and reclean to a total of 40 gallons a day), plus a strict mineral and chemical balance in the salty, colloidal sea that still surges inside us, involving a close coordination with the lungs, heart, liver, pancreas, etc., not to mention the sugar concentration, the acid-alkali balance and the temperature, all of which are intimately monitored by the nerves under the central supervision of the brain.
Glands, although minor organs, are nonetheless essential parts of the body. Consider tbe female breast with its system of some eighteen little rivers of milk, each with thousands of tributaries, combining into a common delta at the nipple. It is something like an extension of the lung, only its millions of alveoli exchange not carbon dioxide for oxygen but rather blood for milk, assembling (with the aid of hormones) long casein molecules out of short amino acid ones. Without the breast few babies (outside modern civilization) could live. And it is made possible by a single microscopic droplet of the hormone estrogen secreted at puberty by the ovaries, which transforms a skinny girl into a shapely woman ready for pregnancy. The adrenal, thyroid, pituitary, gastric, salivary, sweat, tear and numerous other glands also exude comparably potent hormones that carry their specific messages and cast their mysterious influences over every part of every creature endowed with them.
Hormones, created as needed, fortunately seldom seem to accumulate in bothersome amounts, and oxygen, though vital, is something bodies on Earth do not normally need to store in quantity since they can simply inhale it as they need it from water or air. But almost all other important body substances, including trace metals, being not breathable, must be tucked away somewhere for ready availability. Of these the most storable of all is fat which, being 88 percent carbon and hydrogen, is chemically close to gasoline and other hydrocarbon fuels, its favorable energy-per-pound ratio enabling birds and insects to fly and other animals to go long distances in search of food. As it is usually stored just under the skin, it also serves as insulation against heat and cold, not to mention acting as a protective cushion and support for delicate structures, such as joints, kidneys, eyes and sex organs.
But the most important thing we haven't yet gotten to in discussing the body is its system of replacing itself in evolution through reproduction - something that unavoidably (but not unwillingly) leads us into the ever-fascinating subject of sex.
Chapter 5
The Complement Called Sex
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AS I GAZE PENSIVELY out of space at the pale, plump Earth, Venus seems so close behind me that I could almost be looking out of her eyes. That would be appropriate too, because she is a symbol for fertility, which is what this chapter is about. Indeed the continuum of life on any planet depends on fertility, which of course
means continuous renewal, usually termed reproduction. And the most obvious mechanism of reproduction is founded on the complement called sex.
Exploring this subject in evolution, one of the first things we discover is that sex evolved very early on Earth, in fact long before death, which, as we will see in Chapter 20, is mainly associated with multicelled organisms. This means that sex goes back to such simple life forms as amebas, bacteria and viruses, among whom everything seems to have been tried from "birth" by sprouting buds to "sex" without gender and "death" by fissiparous propagation. Does that leave "love" an art? Or is it just something one falls into?
Starfish, you know, get offspring by occasionally releasing an arm. And, in most very primitive creatures, sex is not absolute but relative, the differentiation into maleness and femaleness appearing in a wide graduation of degrees. It is enough to make one wonder what sex, in its essence, really is. And whether sex plays half so important a part in reproduction as most humans are brought up to think.
RELATIVITY OF SEX
The general notion in the eastern Mediterranean region before the emergence of the Hebrews or the Greeks was that sexual attraction is due to the two sexes having originally been one - and this was reiterated from Genesis, wherein woman was created from part of man, "therefore shall a man... cleave unto his wife, and they shall be one flesh," to Plato's Symposium, in which Aristophanes observes that man's joining woman reunite s "our original nature, making one of two." Wasn't this after all just one application of the long-accepted concept of gravity as caused by the tendency of like to seek like, of the yearning of free stones to hug the stony ground, of smoke to rise up and embrace the cloudy sky?
Dr. Alfred Kinsey threw some scientific light on this theory in the 1940s, when he discovered that, in humans, there is actually less difference between the sexes than among individuals of the same sex. And yet, even before birth, curious disparities appear. Girls on the average develop faster in the womb than boys and the female heart beats faster. After birth, a girl seems more sensitive, reacts more strongly to removal of a blanket or to a touch. Also she learns to talk earlier and better and is more interested in people. A boy, on the other hand, is more independent and self-reliant, more interested in inanimate objects. Confined alone in a strange pen, the girl is apt to cry, while the boy tries to find his way out.
Good evidence for the closeness of the sexes can be found in the successful treatment of several cases in this century in which a baby boy's penis was accidentally cut off - after which, with the help of reconstructive surgery and hormones, he was "reassigned" as a girl and brought up to live a happy and "normal" life. As long as such reassignment takes place before the age of about four years, it seems to work well, as "she" doesn't remember being "he" and the psychological conditioning almost takes care of itself. And should the reassignment be made while the embryo is still sexually undifferentiated (during the first 16 weeks of pregnancy), it can be done with hormones alone.
In the case of animals, especially cold-blooded ones, changing sex is relatively easy even when the young one is half grown, because such measures as increasing feeding may turn a male into a female. So will a change in temperature. Or, in the case of a warm-blooded creature, it can be done by extracting ovaries to switch, say, a hen into a cock. As a matter of fact, sex reversals happen naturally in many species. Quahogs, I am told, are born and grow up male, but later half of them turn female, undergoing a sort of sexual demi-death, perhaps when the activity of youth shifts toward the passivity of age. Slipper shells do this too, and cup and saucer shells, commencing every season as boys, but almost all of them saucily switching later through a phase of ambisexuality into adult females - leaving only a few stragglers to linger on as solitary male bachelors.
Sex among these lowly folk seems to depend a great deal on food, since the best-fed individuals turn female the earliest, while the poor scrawny ones get left behind as males (although the opposite happens in the case of oysters). In some species, such as the marine worm Ophryotrocha, if the portly young females are later underfed they revert back into males again. Indeed among most primitive creatures of the sea and practically all insects it is a general rule that the smaller individuals are males and the bigger, fatter ones females, the basic reason being that the essential female function is to produce and feed young, while the only important thing expected of a primitive male is to dart blithely about fertilizing every egg in reach with no ensuing responsibility.
It may surprise you to know that fish have evidently evolved the easiest and quickest sex-reversing capacity of any animal, some species not only changing from male to female as they grow but a few, like groupers and guppies, developing the ability to switch sexually back and forth within seconds, almost as readily as you shift gears in your car. If two girl guppies meet while feeling amorous, an ichthyologist told me, one is likely to start turning into a boy so he can mate the other. But occasionally it happens that both shift at the same moment and find themselves still stymied as two boys ten seconds later. And this sort of flipping to and fro can theoretically continue several times, as with people frustrated in trying to get by each other on the sidewalk. In practice, however, the experts say, such an impasse with guppies usually results in a furious fight, with the winner, oddly enough, emerging as a female who somehow forces the other to stay male.
This brings up the interesting point that the male by no means always dominates the female in nature, doing so mainly where intromissive copulation gives him the unilateral potentiality of rape. But, as that male advantage is lacking among most birds and simpler animals, mating is often initiated by a bigger, stronger female. Furthermore, many primitive creatures (including plants) are hermaphrodites who possess both male and female organs, so mating may go both ways at once. In fact the guppy's flexibility comes from having both testicles and ovaries with some sort of valve that switches the flow from milt to roe. Yet true hermaphroditism (offering simultaneous sperm and egg flow) is entirely normal among most plants and many animals, from snails, who make love with their feet, to earthworms, who commonly emerge from the soil to court one another at night on lawns, spending happy hours adjusting and aligning themselves head to tail and tail to head, with the aid of a sticky mucus they exude, so that the sperm pores on the fifteenth segment of each worm exactly coincide with the egg pores on the tenth segment of the other worm.
Most such hermaphrodites thus have little difficulty begetting enough offspring to keep their population up, but, in times of famine or stress, when they don't meet each other so often for cross-fertilization, each one still has the possibility of fertilizing itself by uniting its own sperm and ova. Indeed a dynasty of laboratory snails has actually been kept going on self-fertilization for 90 consecutive generations (during 20 years) without noticeable loss of vitality. And some kinds of arrowworms have even been found to prefer self-fertilization and apparently use it exclusively in their natural environment in the deep sea.
Hermaphroditism and sex reversal are not the same thing as homosexuality, as is evidenced by their comparative rarity among the more highly evolved creatures all the way to man, who, nevertheless, is occasionally known to shift gender and has actually (in very rare cases) managed to function as both a male and a female at the same time. The most striking example of a well-adjusted human hermaphrodite I've heard of is the individual reported in Lisbon in 1807 as having normal sperm-producing testicles and "some beard on the chin" but otherwise the appearance of a slim-hipped, attractive girl with graceful figure, adequate bosom and charmingly feminine voice, not to overlook the usual female organs which functioned well enough that she-he had already been pregnant twice between presumed affairs in which he-she may in turn have impregnated others!
Easier to understand, I think, is the mental, emotional and spiritual side of the shift of gender - something beautifully explained by the English writer James Morris who, despite his warm relationship with a loving wife and four children, recently became Jan Morris (
female symble) after ten years of taking female hormones and undergoing surgery. "From the age of three I always knew my gender was feminine," he allowed. "Not my sex but my gender. Gender is more important than sex, and more subtle. It's not a matter of body or organs. Or even chemistry. It's mystical ..."
After the operation "she" first felt astonishment, then joy. "She" literally sang. On reflection "she" described it as a "rebirth. ""I had a loss but also a discovery and a gain." Asked how "she" now felt about "her" former wife, "she" said, "It made no essential difference. We will always love each other no matter what. If, instead of a woman, I had turned into a horse, I'd love her just as much. And how interesting it would be!"
ORGANS
The organs and techniques of "love," like other aspects of life, are surprisingly various, and new ways are apparently being tried out in an endless sequence as evolution unfolds. Both the kangaroo and the opossum, for example, have forked phalluses that more than conveniently fit into their mate's forked vagina, while snakes and lizards have completely double ones (called hemipenes) that erect "inside out" like fingers of a rubber glove and work separately, each in its own time sliding into the female's single anal-vaginal passage (called a cloaca). The gray squirrel, on the other hand, has a hooked penis, the mole shrew an S-shaped one with flanges for taming his own little shrew, and a number of animals including the spider monkey, wild cat, lynx and puma all have barbs on theirs, indeed horny ones that point backward and latch upon complementary "projections" in the vagina that did not evolve there likely by pure coincidence. In each of these cases the locking mechanism tends to hold the mated pair together, much as dogs are sometimes locked by the knot midway on his organ, and, despite all their caterwauling, perhaps this is nature's way of accomplishing for cats some of what the Dyak people have sought for humans by embedding silver knobs (called ampallang) in the penis to increase friction, or the Celebesian custom of encircling it with goats' eyelashes for enhancement of feminine delight. The only animal I can think of who has gone further is the Abyssinian bat whose member is densely coated with bristles. On which I've seen a meticulous zoological report saying that it works like a bottle brush.
