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

BOOK 1

a little worm-like tube, three or four inches long, and ending blindly, the appendix. In man these structures have no functions that other organs cannot carry out—indeed, it is probably better to be without an appendix, for it may be the seat of acute and even fatal inflammation.

It is improbable that the human large intestine plays any important part in digestion. People can live to be healthy and active after its removal. When the remnants of our meal pass the ileo-caecal valve they have lost at least ninety-five per cent. of their fats and carbohydrates, and they contain less water than the amount shed into them by the various glandular secretions they have received. The greater part of

Fig. 33. A small part of the inner surface of the intestine,

magnified.

The finger-like villi absorb food ; glands which make a digestive juice. guard-house against bacteria.

this residual water is absorbed in the large intestine. As far as other substances are concerned, although the possibility of further absorption during the slow progress of food along the large intestine (a progress that takes about twelve hours) cannot at present be absolutely denied, it is at least certain that whatever occurs is insignificant. Moreover, the large intestine is a hotbed of bacterial putrefaction. Any bacteria that can successfully resist our digestive processes flourish in this warm, relatively restful situation, and consume the undigested parts of our meal. It has been calculated that as much as fifty per cent. of the faeces (exclusive of water) consists of living and dead bacteria. Tt is unlikely that much of the other half

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THE SCIENCE OF LIFE

among them are the mouths of The oval in the middle is a

CHAPTER 2

is food residue, since such residue has been used to build up bacterial bodies or as fuel for bacterial activity. Most of it is dead cells that have dropped off the intestinal wall, just as dead cells are constantly peeling off our skins. This dropping off of dead cells has, of course, nothing to do with nutrition, and it is remarkable that professional fasters have produced faeces after taking no food for thirty days, and that faeces can be generated in the colon even when its connection with the small intestine is artificially closed.

It is interesting to point out in conclusion here that Mr. Everyman is fitted up with a food canal which is certainly too long for his present needs, and that even in the case of the healthiest human being a fermenting multitude of these alien bacteria form a frequently mischievous foreign quarter in the intricate community of the body. They increase and multiply in complete disregard of their host and may cause him the distresses and inconveniences of colitis and various other annoyances. In the mouse the caecum and the large intestine have definite and essential uses. To the mouse they are indispensable.

We have already pointed out that Mr. Everyman gets his food more regularly and surely than does the mouse. It is also better chosen, and it is prepared in various ways that anticipate digestion. The hungry mouse in hard times will do tremendous feats of digestion, from boots to carpets and grease-paint, that are quite beyond the present powers of Mr. Everyman. For him, under existing conditions, the small intestine seems to be nearly all that he requires. Intestinally he is over-equipped. An eminent London surgeon has declared that Mr. Everyman might with advantage be deprived of stomach, appendix, and large intestine, and benefit (ultimately) by the change. Perhaps as the enlargement of his belt begins to trouble Mr. Everyman he may be persuaded presently to try this heroic way back to the slenderness of youth.

§ 8

The Continual Struggle Against Infection and Chill

Before we conclude this résumé of the Body-machine or Cell-community which constitutes the material substance of Mr.