The science of life : fully illustrated in tone and line and including many diagrams

THE GOMPLEX BODY-MACHINE AND HOW IT WORKS

they form films over the other food-substances, and interfere with their digestion also. And the pent-up bile-pigments force their way into the blood, and are manifested by yellow eyeballs and yellow skin. Our complexions go yellow with this pigment, and our faeces white for lack of it.

Nevertheless, the liver does not deserve most of the abuse that is showered upon it. It is imagined as a capricious, temperamental gland, the most delicate part of our bodies. But, in fact, most of the headaches and furred tongues and losses of appetite that we call “ bilious attacks”? or ‘‘ touches of liver * have nothing to do with that organ at all; they are disorders of the stomach due to errors in eating and drinking. Even jaundice originates in most cases in trouble in the intestine or bile-duct, not in the liver itself; the yellowness we just noted is, in fact, due to the liver faithfully carrying on its duty, although the avenue of escape of its secretion is closed. Wherefore, if the reader is in the habit of maligning his liver we appeal to him to revise his estimate. It is an ingenious, busy organ, doing responsible work in a very exposed situation, and any irregularity in its function is far more likely to be due to the way he treats it, or has treated it in the past, than to any inherent frailty in its own constitution. In this manner, then, most of our

food-stuffs are absorbed and scru- Caecum

tinized. But there is a curious

exception, for digested fats are not Appendix

sent to the liver; they travel to

the heart by another way. We Fig. 32.

have already referred to the oozing

out of lymph through the capillary

walls that goes on in all our tissues and its return by the lymphatic system to the heart. Now in the villi this ooze is particularly copious, and it is this stream that carries the fats away when they have been absorbed. This is probably because of the stubborn exclusiveness of fats that we have already noted. As soon as they have been absorbed by the villi, the glycerin and fatty acids form fats again, and these run together into droplets ; these droplets, if they were sent by the blood, might clog the liver capillaries, and obstruct the portal circulation. After a meal rich in fats, the lymph contains enormous numbers of these droplets. They give it a milky appearance, which can be

traced up to the thoracic duct, and even into the great veins.

When the enzymes have finished their work and when all that we require has been absorbed, there is still a certain residue of our meal left over. There are substances that are useless for food, and substances that might be useful if we had a chemical apparatus for dealing with them—such as cellulose, the carbohydrate wall of plantcells, which forms a large part of the food of a cow. Moreover, since digestion is not a perfectly efficient process, there is a small proportion of good food that has successfully run the gauntlet. Before it is dropped

Large Intestine

Small! Intestine

An organ that we should be better withoutthe human vermiform appendix.

overboard, this residue travels about a yard and a half, up the right side of the abdomen, across the top, and down the left, along a broad tube, the large intestine. On its way it undergoes further alteration, not always to the benefit or comfort of Mr. Everyman. J

The opening of the small intestine into the large is guarded like its opening into the stomach, by a muscular sentinel, a ring muscle, in this case the ileo-caecal valve. From this point the large intestine, or colon, pursues its devious course to the anus. It is curious to note by the ileo-caecal valve a small pouch leading out of the colon, known as the caecum, and leading out of this

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