CHAPTER XXXIV

THE BLOOD AND ITS CIRCULATION

RED, crimson, scarlet, hot, the river of life, the carrier of all that is good and all that is bad by its myriad streams through our bodies; the rarest, most precious, most gorgeous of fluids; the daughter of the salt ocean, finer and more worshipful even than the waters of the great mother, the sea; the badge of horror and of accursed cruelty, yet also the emblem of nobility, of generosity, of all that is near and dear, of all that is splendid and beautiful; the blush of modesty and the flag of rage; the giver of coral lips and glowing cheeks to youth and health, and no less of the ruddy nose which women hide with powder and men bravely bear without concealment! Such is the blood, and it is no wonder that the mere sight of it has always had an overpowering fascination for mankind.

The wild people of the Solomon Islands, when they see a drop of blood flowing from an accidental scratch of hand or foot, say, "I must go home; some danger is at hand; the blood has come to tell me!" Sorcerers and witches of all times have endeavoured to procure a few drops of the blood of their intended victims in order to "work spells" upon the precious fluid, and so, according to the theory of "contagious magic," upon the person from which it came. In Italy to-day, as in this country a few hundred years ago, when some one's nose bleeds, a Latin hymn to the blood (beautiful in its conception) begging it to stay its flow, as it did when the soldier's spear pierced the side of the crucified Christ, is sung. In a village in the hills near Naples I was taken with an attack of nose-bleeding, and bathed my head with cold water from a pretty fountain which supplied the people with its pure stream. The women brought handsome old brass basins and embroidered cloths of the most delicate linen for my use. I heard a strange chanting behind my back as I stooped over the water, and when the bleeding had ceased I found that an old man of the village had placed two straws in the form of the cross on my shoulders, and was reciting the ancient Latin hymn to my overflowing blood! I obtained afterwards from a friend the words of the same hymn as used in long-ago days in English villages.

One primitive race if not others, namely, the Australians, take a very prosaic and business-like view of the blood. They use it as an adhesive--a sort of liquid paste or gum, always ready to hand! In order to fasten feathers or other decoration to a pole, the Australian "black fellow," without wincing or hesitation, and as a matter of course, makes a cut (with a sharp piece of stone or glass) in his own arm, and uses the convenient blood. It also serves them as paint, as it has served many a chieftain of European race for signing his name, and many a prisoner for writing in the absence of ink.

There is for some people a fascination in the sight of blood which must not be mistaken for cruelty, although it is accompanied by dangerous and undesirable emotion. Just as other emotion-producing experiences--such as the sight or hearing of torture, of hairbreadth escapes, and of ghosts--produces uncontrollable repulsion and horror in some people, and to others (or even to the same people when in another state of health or mental balance) actually gives a pleasurable sensation (exquisite shudderings, as the French say), so does the sight of blood or even the mere hearing of the word "blood" act differently on different people. Every one who has witnessed a Spanish bull-fight knows that it is not any desire for, or enjoyment of, the sight of pain which excites the crowded mass of spectators. There is no "cruelty," in the proper sense, in their state of mind, no pleasure in witnessing pain--a thing which, terrible as it is to think of, yet does exist naturally in mankind, and has to be, and is, repressed and absolutely got rid of in the course of the humanizing education of civilized mankind. The spectators of the Spanish bull-fight are primarily under the spell or fascination of the sight of blood, and in a less degree they are attracted by the wonderful exhibition of skill and strength on the part of the matador and his troop. The crowd excitedly acclaims the first drops of blood which the splendid bull is made to shed. They buy, after he has been killed, the paper-winged darts smeared with his blood. The colour, the mystery, and the magnificence of blood produces in them a violent emotion. It is to them a delight, but only a single step separates their delight from pain and actual physical distress. The most absolutely nauseating smells are very nearly identical with delightful perfumes, and we all know how readily a taste may be acquired converting the former into the latter--as in the case of the (to most people) foul-smelling East Indian fruit, the durian, and of rotten cheese and "high" game. We also know that a sudden revulsion of "feeling" may occur in regard to hitherto approved smells and flavours, so that headache, vomiting, and even fainting may be produced by a smell or flavour which was previously found a favourite beyond all others.

So it is with this great and mysterious thing--the blood. The sight of it nearly always produces emotion and excitement, but if these emotions are not accompanied by an unreasoning joy and delight, they may result in equally unreasoning and uncontrollable disgust, horror, and often a sudden and unaccountable collapse. Some time ago in a popular lecture on the colouring matter of the blood I had no sooner said the word "blood" than a gentleman in the front row fainted and had to be carried out. Men are more susceptible to this curious effect of the sight or thought of blood than women. Often they do not know that they are so, and are as astonished and perplexed by the sudden fainting as are onlookers and as are, for the matter of that, physiologists and psychologists. It is a common experience of medical men who vaccinate adults, when there is a scare about smallpox, that at the sight of a tiny drop of blood caused by scratching the arm with a lancet, men frequently faint, whilst women rarely do so. Great, burly, red-coated soldiers, and also athletic schoolboys, have been especially noted as fainting when vaccinated. Maid-servants rarely faint under this absurdly trivial ordeal, whilst the butler and the valet much more frequently do so. Here is, indeed, a curious and unexpected difference between men and women which I commend to the consideration of those who are discussing the desirability of admitting women to the parliamentary franchise. It is an unexplained instance of the influence of the mind on the body, and until it is better understood, one must not conclude that the difference is a proof of superior fitness for participation in political affairs.

I trust that none of my readers may suddenly faint on reading this page, but should be glad to hear of any experience of the kind. It is readily understood when the profound impression produced by the colour of man's blood is considered, that the great inquirer Aristotle and a good many uninquiring people of the present day should overlook the fact that the lower animals have blood. The insects, crustaceans, mussels, clams, snails, and cuttle-fish, and many worms have true blood and a heart and blood-vessels, but in most of them the blood is colourless, or of a very pale blue tint. Hence, like the lymph described in the preceding chapter, it escapes attention, and Aristotle called them all "blood-less animals." The fact is, however, that not only do they possess colourless or pale blue blood, but that the bristle-footed worms (earth-worms and river-worms and marine Annelids) and even the leeches possess bright red blood contained in a complete branching network of blood-vessels, whilst here and there among the otherwise colourless-blooded molluscs and crustaceans and insects we find isolated instances of the possession of red blood. Thus the flat-coiled pond-snail, Planorbis, has bright red blood, so have one or two bivalve clams, so, too, has an insect larva (known to boys as a blood-worm) that of the midge (Chironomus), so, too, have some small fresh-water shrimps, and also a single species of star-fish and one kind of sea cucumber!

I explained in the previous chapter that the blood of the vertebrates may well be called hæmolymph, since in them the colourless, slightly opalescent fluid called "lymph" is continually poured through certain openings into the red blood, and mixed with it. In the earth-worm and other lower animals the red-coloured blood, or its equivalent--the "hæma," as distinguished from the "lymph"--is held in a closed system of vessels, and does not receive any of the lymph. When examined with the microscope, the blood, or hæmolymph, of man is found to consist of an albuminous, slightly sticky liquid, in which float an immense number of "corpuscles"--minute bodies, some rounded, some irregular, some bun-like, and some spherical. The most abundant of these are the "red corpuscles," of the shape of buns, slightly depressed on each surface. Three thousand two hundred of them could be placed lying flat side by side along the space of a measured inch. They appear pale greenish-yellow in colour under the microscope, but in quantity, lying one over the other, they allow only red and some blue light to pass through them, and so have a fine red colour. They consist of a small quantity of albuminous matter and water, and of a large proportion of a red-coloured, crystallizable, chemical substance dissolved in them, called hæmoglobin, or blood-red. It is this hæmoglobin which performs one of the most important duties of the blood, since it combines with the oxygen of the inspired air when the corpuscles are flowing through the fine vessels of the lungs, and carries it to the tissues in every part of the body, which greedily take the oxygen from the red corpuscles.

The red corpuscles of man's blood and that of the hairy suckling animals--the mammals--are not nucleated cells, but are regularly formed and renewed as they daily wear out, as fragments of larger mother-cells, which break up into these corpuscles, in the marrow of the bones, and some other situations where they are found. In all other vertebrates the red blood corpuscles have a kernel, or dense nucleus, and are complete "cells," usually oval, smooth and flattened in shape--a curious difference not easily accounted for. There are in a pint of the blood of an average man about two billions of these red corpuscles, and the amount of blood in the body is about one-twentieth of the total weight of the body--say, in a man weighing 160 lb., about 8 lb. or pints of blood. The clear, colourless lymph existing in all the lymph spaces of the body is probably about twelve pints. In many animals the red corpuscles are much less numerous than in man; for instance, a drop of human blood contains a thousand times as many red corpuscles as does an equal-sized drop of frog's blood. It is true that the frog's red corpuscles are a good deal bigger than those of man, but the result is that the human blood is some hundreds of times richer in hæmoglobin than the frog's, and has a proportionately greater power of carrying oxygen from the lungs to the tissues, and keeping up the slow, burning process, or oxidation, upon which the activity of the body, as well as its warmth, depend. The body depends upon its supply of oxygen as a steam-engine depends upon the oxygen of the air, which keeps its coal-fire burning.

The pace of the blood-stream which is produced by the force-pump action of the contractions or beats of the heart is tremendous. It courses along at the rate of ten inches in a second in the big arteries and veins, and it has been carefully ascertained by experiment that a heartful of blood (which in a big man is about half a pint for each half or "side" of the heart)--or let us speak of a single corpuscle--is driven out of the heart through the great artery or aorta to the most remote parts of the body, and is back again at the heart, after running through endless branches of arteries, smallest capillaries, and thence into fine veins, bigger veins, and the biggest vein, in twenty to thirty seconds, the time occupied by twenty-five to thirty heart-beats. The walls of the arteries are firm, though elastic, and it is no wonder, with this tremendous pressure and pace on the liquid within, that when an artery is cut the blood spurts out to a distance of several feet.

The colourless liquid of the blood contains, besides the red corpuscles floating in it, others brought to it in the lymph and derived from various connective-tissue spaces and special nodules or "glands." They are outnumbered by the red corpuscles in the proportion of five hundred to one. They are colourless, and bigger than the red corpuscles. Most of them continually change their shape, and consist of active, moving protoplasm. These are the "phagocytes," which, besides acting chemically upon the constituents of the blood-liquid, take into their substance (as does the amœba or proteus-animalcule) and digest and destroy all foreign or dead particles, and the bacteria which may find their way into it. They pass out, forcing their way through the excessively thin walls of the finest capillaries--blood-vessels not wide enough to admit two of them side by side--and enter, to the number of thousands, the tissues which have been wounded or poisoned by bacteria, to carry on their all-important protective "scavenger" or "police-constable" work.

Inflammation is the slowing of the blood-stream by dilatation of the vessels at an injured spot, in order to allow the phagocytes to make their way out of the blood-stream into the tissues, and so get to close quarters with the enemy. There are other excessively minute dustlike particles called "platelets," which are sometimes very abundant in the liquid of the blood. Besides the duties of oxygen-carrying and scavengering the blood has other great and vitally important business. It has to distribute nutriment, to pick up waste oxidized chemical products and get rid of them, and to distribute and equalize the heat which it carries around the body like a perfect hot-water warming installation.