LETTER XV.
THE NOURISHMENT OF THE ORGANS.
When I said formerly that our dear and wonderful steward the blood, was everywhere at once, you little suspected the prodigies involved in that everywhere. But you will have a glimpse of them now, when I tell you it is at the extremities of the capillary arteries that he carries on his distribution of goods, and accomplishes a mysterious act of nutrition; a wonder much greater even than that of which we have just spoken. Here, indeed, the question is no longer mechanical divisions, whose delicacy, surprising as it may be, is yet within our powers of comprehension. What is more surprising still, what moreover we cannot comprehend at all, is the delicate sensitiveness of tact—I would almost say of instinct—with which each one of the million millions of tiny atoms of which our body is composed, draws out of the blood—the common food of all—exactly that aliment which is necessary to it, leaving the rest to his neighbor, and this without ever making a mistake.
You have never thought about this; for children go on living at their ease, as if it was the simplest thing in the world to do; never suspecting even that their life is a continued miracle, and never, of course, therefore, feeling bound to be grateful to the Author of that miracle. And alas! how many hundreds of people live and die children in that respect.
But what would happen, I should like to know, if the eye took to seizing upon the food of the nail, if the hairs stopped on the way what was intended for the muscles, if the tongue absorbed what ought to go to the teeth, and the teeth what ought to go to the tongue! Yet what prevents their doing so? Can you tell me? They all drink alike out of the same cup. The same blood goes to furnish them all. The substances that it brings to the eye are the same as those which it brings to the nail; and nevertheless the eye takes from it that which makes an eye, and the nail that which makes a nail.
How is this done, do you think? that is the question.
When the doctors reply to this, that each organ has its peculiar sensibility, which makes it recognize and imbibe from the blood one particular substance and no other, they are strangely mistaken if they flatter themselves that they have really answered anything. They have done nothing but reproduce the question in other words, for it is precisely that sensibility which requires explanation, and to tell us that it exists, does not explain much, you must own. If you were to ask why you had got a headache, and some one were to reply that it was because your head ached, you would not be much the wiser I fancy.
Each of our organs, then, may be considered as a distinct being, having its separate life, and its particular likings. These organs behave towards the blood like men who recognize some friend in a crowd, and proceed to seize him by the arm; and when I told you just now that they never made a mistake, I spoke of their regular course of action in ordinary circumstances. Like men, they also make mistakes sometimes, in certain cases; and take one substance for another, or do not recognize the one they are in need of; an unanswerable proof that at other times they exercise a sort of discernment, and do not act by a sort of fatality, as one might be tempted to believe. Look at the bones, for instance. They are composed of gelatine (which cooks serve up under the name of meat-jelly, but which would be more properly called bone-jelly), and of phosphate of lime, a kind of stone of which we have spoken before, if I remember rightly, and from which they get all their solidity. Originally, the substance of the bone is entirely gelatinous, and the phosphate of lime deposits itself therein by degrees, as time goes on, and always in greater abundance as we advance in age.
Properly the bones borrow only gelatine and phosphate of lime from the blood. But when they come to be broken, their texture or tissue inflames in the fractured place; and then it changes its tastes, if I may so express myself; and, lo and behold, extracts from the blood that which forms certain little fleshy shoots, which unite together from the two sides of the fracture, and so mend the broken bone. Here is one exception to the rule.
Again, in certain diseases, the bones suddenly quarrel with the phosphate of lime; they will not hear of it any longer, they will not accept a fresh supply; and as the old wears out by degrees, by reason of the continual destruction of which I spoke the other day, the bones become more and more enfeebled, and soon can no longer support the body. A second exception this.
Finally, when old age comes on, the bones end by being so much encumbered with phosphate of lime, that they have no room to admit the fresh supply which keeps coming to them in the blood. What becomes of it then? It goes to seek its fortune elsewhere; and there are charitable souls, who forgetting their instinctive antipathies, consent to give it hospitality, though much to the prejudice of the poor old man himself, who is no longer served so well as formerly, by the incautious servants who have allowed themselves to be thus fatally beguiled; but no one consults him. It is the arteries especially, and sometimes the muscles, which take this great liberty, and it is not unusual among old people to meet with these fairly ossified—that is to say, changed into bone, thanks to the phosphate of lime with which they have consented to burden themselves. This is a third exception, and I will spare you any others.
What may we infer from all this, my dear child? Well, two things. First, that we know nothing at all about the whole affair; a fact which at once places us on a footing with the most learned philosophers in the world. Secondly, that our body is a perpetual miracle; a miracle which eats and drinks and walks, and which we must not look down upon for so doing: for God dwells therein. I should have to come back to this at every turn, if I wanted to fathom everything I have to tell you about. Each tip of hair which you grow, is an incomprehensible prodigy which would puzzle us for ever, if we did not call to our aid those eternal laws which have made us what we are, and to which it is very just our spirits should submit, since we could not exist for one second were they to cease from making themselves obeyed in our bodies.
Reflect on this, my dear little pupil. Young as you may be, you can already understand from it, that there is above you something which demands your respect. The good God, to whom your mother makes you pray every night, on your knees, with folded hands, is not so far off as you might perhaps suppose. He is not a being of the fancy, secluded in the depths of that unknown space which men call Heaven, in order to give it a name. If His all-powerful hand reaches thus into the innermost recesses of your body, His voice speaks also in your heart, and to what it says you must listen.