A CIVILIZED MAN never knows when he may be called on to defend the citadel, so to speak, against the next charge of the barbarians with their odd cries and stone hatchets.

So it is not one day too soon for us to contemplate Miss Furbish's lousewort and what it means to this nation and how we must order ourselves in the struggle.

Miss Fubish's lousewort, as everyone will soon become aware, is a rare plant facing extinction along the banks of the St. John River in Maine. There seem to be perhaps 800 individual plants in the world, and most of them would be lost if nothing were done to protect them from the projected ruin of their natural home.

Two dams are proposed there that would obliterate Miss Furbish's lousewort's habitat.

The law of this republic forbids the use of government money for any project that would grievously damage a plant so rare as this lousewort.

But there is some is good news today. The Army Corps of Engineers (the dam or the goddam people, depending on your point of view) themselves discovered the existence of this rarity in their path. They themselves called attention to it, and asked the Fish and Wildlife Service (guardian of threatened louseworts) how to proceed.

This is one of the most complex situations that has come before the government in administering its laws on endangered life. Through a miracle, you might almost say, it seems probable that the Engineers will be able to save the lousewort, through propogation and transplanting to another site, short of a constitutional crisis.

Mind you, it is one thing to talk thing else to find a site and establish a rare plant there so that it continues to breed.

It is enormously important, though, that the Enginners faced the problem straight, without subterfuge and lies, and the guardians of endangered life are little less than thrilled at this example of cooperation in fulfilling the law.

As things stand now, the Engineers commit themselves to finding the means to preserve the lousewort in another location. The enforcers of the law will study the solution that the Engineers find, and if all goes well, as it is expected to, there will be no objection to the dams on behalf of the lousewort.

So far, so good.

Unfortunately, the know-nothings and roofy-toot lunkheads of the continent - a species in no danger of extinction - have seized on the delightful name of the plant to make sport of the law.

We may hear much from them in the months ahead.

They are sure to point out this plant is not very handsome and has no known economic, medicinal or especially esthetic use. It could vanish completely and we would not be the poorer.

Just yesterday I noticed one of those he-man type articles on the editorial pale of The Wall Street Journal saying, in effect, we have lost our minds in American law.

Snail darters, Miss Furbish's lousewort, anopheles mosquitoes and diamondback rattlers (it goes on) could vanish utterly and the "average voter" would say good riddance.

It is possible that the average voter would in fact say good riddance, if he relied only on a press that said the whole business of endangered species is a budget of nonsense.

But the average voter is also the average American, and is quite capable of giving attention to something he formerly paid no attention to, and quite capable of changing his mind on Vietnam, Watergate, snail darters and louseworts.

THis may be the place to mourn that four-letter Anglo-Saxon words are now so unfamiliar that "wort" is commonly mispronounced. It is like all those other words spelled with an "o" and pronounced with an "u." (Work, word, worth, whorl, worm, world and so on.) It has been in the language for only 1,100 years - too new for us to have the hang of it.

A wort is a plant.

There are many sorts of louseworts (the name, by the way, was given by shepherds who noticed that fields where this plant grew were the same fields in which their sheep had lice. It is likely that all their pastures had louseworts, or else that all their sheep had lice, no matter what the pasture; but the shepherds are always looking about for something to blame their vermin on).

Many louseworts are common. You could build a dam and never give them a thought. It is just Miss Furbish's louseworth (Pedicuriaris furbishine) that is endangered.

Why, one of might ask, should there be any effort to preserve a plant with no known use beyond the production of infant louseworts?

There are several answers:

1. Our own vast ignorance of this lousewort is no guarantee that it has "no value." The rubber tree only recently came into practical economic use. The penicillin mold was not much esteemed on cantaloupes and its remarkable properties were long unknown.

2. Apart from important human uses that might be disclosed in the future, a plant of no known use to us might be of considerable use to some other creature. If there are only 800 of these louseworts, it is hardly going to turn out that the snail darter, say, desperately requires them for food. But the principle is sound, that life does not exist in a vacuum (except in the immediate vicinity of some typewriters) and what affects the plankton eventually affects the osprey.

3. Even if the plant is of no use to man or beast, there is the esthetic question of the richness and variety of the natural world. Who would want a world without tigers and rattlesnakes, lambs and leopards, Wall Street Journals and Hustlers?

As individuals we may find it possible to live out our lives in such biological and horticultural and faunal slums as downtown Manhattan, but even there the normal heart rejoices to think of wolves and quetzals flourishing in the great world, if not in the restricted prison in which some men are content to live their poor lives.

4. There is the matter of genes. They can combine and segregate in astounding ways. What the lousewort's genes may be worth, a million years from now, we have no way of knowing, but we do at least have the sense to know that once lost there is no way to recreate this stuff of life. If it is argued that men will no longer walk the earth then, that is beside the point.

5. Finally, there is the matter of human honor. Whether is is honorable to bang through the world oblivious to every thing and every creature that does not seem immediately useful for our advancement in our own poor notions (notions all to likely to change as we increase in wisdow) of what "advancement" is.

Or whether it is honorable to brood over the treasure of life and sustain and promote it, to shelter and celebrate it.

Give any man the choice and he will choose, despite his moments of insanity and natural aptitude for going bananas now and again - he will prefer the side of grandeur and richness to the narrow rigid keyholes of locked compartments.

Whether life is a rat race or a garland is a matter of some consequence.

What we conclude, on such questions, affects not merely the lousewort, but the respect with which we hold ourselves and the way we go about doing everything we do.

Nobody is likely to argue that all life must be preserved at all costs at all times.

There may even be occasions for fights of one kind or another that do damage of one kind or another.

With the lousewort, we will hear the argument that we have a choice between a few worthless plants and two vitally important electric generating plants. But as it happens in truth, it appears we can have both the lousewort and the electricity, provided we think ahead and do not just sit on our butts making wisecracks about forms of life we know nothing of.

Sooner or later, needless to say, there will be conflicts far harder than the one presented by Miss F's 1.

How we acquit ourselves then depends on how we have trained ourselves. Wars are won, they say, on playing fields at schools.

Whether we come out on the side of life or the side of electric can openers - a choice that goes to the center of what our own lives are worth - defines a great deal in the way we get on with others and the way we get on with ourselves inside our own hearts.

Some say barbarians will win, and it is worth noticing they have already put rattlesnakes on the worthless list, and no doublt tigers, bears, dogs will soon follow.

There have always been savages at the gate. The question is not so much how savages behave as how we do.

The center is going to hold. One more round.