Natural Wonders

by Edwin Tenney Brewster

If they get by this, we poison them with bile. The bile is made in that most useful organ, the liver, and is partly waste matter, more or less hurtful to the body, which we are getting rid of. So since we don’t want it to poison us, we use it to poison other living creatures inside us.

That, then, is our third line of defense. If the enemy gets by that, then the war has to be fought out in the blood. Even if we win, we shall suffer damage, and very likely take to our beds and have to call on the doctor for reinforcements.

The blood itself, good healthy blood, that is, will poison the germs; for the blood of any sort of creature, as I have explained, will poison any other sort. Besides that, we manufacture special poisons with which to combat each special creature that makes a special poison to assault us. So each side poisons the other, and the battle becomes a question of which can kill the other first. In one case, we are sick and recover; in the other case, we are sick and die.

When the doctor takes a hand in the battle, he begins by giving us food and medicine, to make us strong for the war. Sometimes, besides these, he gives us something which, while it harms us a little, harms the enemy a great deal more. In a few cases now-a-days, he pumps into our bodies some of the blood of another animal, generally a horse, which has been fighting the same disease, and so has its hand in and can manufacture many times as much stuff to kill the germs as we can. Many, many people have been saved by this means, who otherwise would certainly have died.

In a few cases, too, small-pox especially, by means of vaccination, long before the enemy attacks us, we can be loaded up with ammunition to repel the invader when it does come. The vaccination gives a mild form of the disease (not so very mild perhaps you think, when your vaccinated arm gets nice and red); we defeat this triumphantly, but we manufacture so much “anti-toxin” to do it with, that for years afterwards we are all ready for the first germ that shows its face in our blood, and slay him before he gets a chance at us. The “anti-toxin,” as you know, is the substance which we make with which to get back at the germs that are trying to poison us with the “toxin” which they make.

But even the battle in the blood is not fought quite in the open. We have, so to say, breastworks and rifle pits, where we can still make a stand, even after the invaders have gained a footing in our bodies.

Perhaps you have sometimes felt small roundish hard bunches as big as a pea or a marble, under the skin at the side of the neck, under the arm pit, or in the groin. Sometimes these swell up and get sore. These nodules are the lymph glands. They surround the passages through the flesh along which the invading germs are likely to come, after they have burst through the skin. They are then like the fortifications along a road over which the enemy is likely to march. We can feel them only in certain places; but they are all over the body, under the skin, and beneath the membranes of the lungs and the digestive organs, wherever the body is most open to attack.

The garrison of these little forts are a peculiar sort of naked cells, which having no walls or covering to hold them in, can change their shape, reach out, and draw back again, as if they were sea-anemones or polyps or some other sort of water creature, and not part of our bodies at all. These cells are twenty or more times larger than the bacteria. And when the bacteria or other germs come along through the passages of the body on their way to the blood vessels, these guardian cells of ours reach out and grab them, drag them in, and devour them, like ogres that devour travelers who go by their castles, over the high road. Only in this case, our sympathy must be entirely on the side of the ogres.

But these lymph cells do not always stay in the lymph glands. When they like, they let go their anchorage, and go floating off through the blood, or through the lymph; for the lymph is only the watery part of the blood without the red corpuscles, which doesn’t stay in the blood vessels but soaks everywhere through the body, feeding and moistening the cells. These lymph cells, or white blood corpuscles, can go everywhere over the body, pushing and squeezing and elbowing their way among the other cells or traveling in the open spaces between them.

When the enemy enters the body, and begins to poison the blood, the white corpuscles smell them, and at once begin to crawl toward the smell, to reinforce their brothers in the particular lymph glands which happen to be at the point of attack. You get a sliver in your finger. The sliver opens a hole in your defense, and carries in some hostile germs. If, therefore, your lymph cells did not come to the rescue, you would inevitably die of blood poisoning. But they do come to the rescue. The white “matter” or “pus,” which in a few days comes out of the wound, is in large part the dead bodies of the fallen enemy and of the defenders who have perished in the fight. So in general, the invasion is stopped at the first lymph gland. A few thousand white corpuscles fall in the war. The enemy is massacred to the last man. And the body is saved.