The Iranian crisis has inspired hundreds of young Americans to go to their nearest Marine recruiting station.

"But nobody is signing up," laments Brig. Gen. Alexander Patrick McMillan, director of Marine recruiting. "They're just talking."

The Marines, Army and Navy each failed to meet enlistment quotas in November -- a month of fervent flagwaving in this country motivated by the captivity of Americans held at gunpoint inside the U.S. Embassy in Tehran.

Only the Air Force made its quota in November. But this did not stem from any new wave of patriotism. The Air Force signed up all the enlistees it sought in October as well -- the month before the U.S. Embassy in Tehran was stormed. In November, the Marine Corps got only 82 percent of its recruiting quota, the Army 86 percent and the Navy 95 percent.

"It is not a Pearl Harbor," Gen. McMillan observed. "You know darn well the Iranians are not about to invade the United States."

In a way, the limits of contemporary patriotism are defined by those statistics. Without a Pearl Harbor and even with an Iran crisis, the Marine Corps and the other armed services are in a constant scramble to fill their ranks with volunteers. Last year, the Marines fell short and cut their troop strength. This year, the media have reported periodically on "recruiting scandals" in which the recruiting officers break rules in order to sign up young people who aren't really qualified.

Gen. McMillan, as the Marine recruiting chief, sees the corps squeezed by deep social changes in America, by competing options more attractive than the military and by the absence of genuine patriotic motivation.

He enlisted at 17, a poor kid from Queens who in 1946 saw the corps as a way up from poverty and also as a way to serve his country. Commissioned in 1950, having fought in Korea and Vietnam, McMillan rose to the top -- a one-star general at age 50.

"The middle class has deserted the military," the general declared with the characteristic bluntness that has aroused lots of questions from Capitol Hill. McMillan sees the services depending too heavily on the lowest ranks on the economic ladder, taking in too many who simply can't cope either with military discipline or the rigors of modern weaponry.

When he was coming up through the ranks, McMillan saw the military as primarily middle class. Ambitious kids wanted to join and they did.

"Number one, it was patriotic," he said, "and, number two, there was that tangible benefit when you finished military service." A veteran was entitled to a college education under the G.I. bill.

"With the all-volunteer force, we've said it's a job," McMillan complained. "We've implied that it's purely economic. How do you attract a thinking middle class young man to the military when you do away with the intangibles as to why he should do it?"

What should the government pay a man to risk his life in combat? McMillan thinks that the "economic incentives" enacted by Congress miss the point.

"When I went to Vietnam or Korea, we got $50 combat pay," he remembered. "Nobody fights in the military for $50. When you get right down to it, if they want to give me 50 bucks, I'll take 50 bucks, but what's the value of my life? It surely isn't 50 bucks. It surely isn't $750.

"So, you either join the military because you believe in your country -- you have that patriotic feeling and the whole system supports that feeling -- or you destroy that feeling by slopping it over to the economic side of the house."

Congress, as McMillan sees it, is displaying tunnel vision by looking only at the economic equation.

"Increase the pay of the private; give him more of this; give him a bonus to come in. But we never really go back to the central core issue which is: why should a young man serve?"

In answering his own question, McMillan sounds as if he agress with those military leaders who, at the same time they are striving to fill quotas to make the all volunteer force work, believe down deep that only some kind of mandatory service will restore the sense of obligation.

He stopped short of recommending that step, declaring: "He should serve because it's an obligation to his country . . . Without a draft, there's no way to make that obligation a truly imposing force. The middle class, the quality guy you're looking for, has deserted the military. We don't really have an anti-military sentiment in the nation. We have, basically, a non-interest in the military."

One Pentagon study of the all-volunteer force found, for instance, that 53 percent of the enlistees in November, 1975, were from families with less than $10,000 income -- while only 31 percent of the general population belongs to such low-income families. A look at 1972 volunteers found they were 1 1/2 times more likely than non-recruits to have fathers with less than a high school education.

While 13 percent of American young people 17 to 24 years old are black, 24 percent of 1978 Marine recruits were black; for the Army the figure was 34 percent.

Young people, McMillan continued, "have found another way to do the thing that they're interest in.

"They've found that they don't have to go in the military to achieve education." For one thing, they can go to low-cost junior college near home -- the new opportunity for education created nationwide in the last generation.

This option enables high school graduates who previously wouldn't have gone to a university to delay making a career decision until they are older. "When I was a kid of 17, I was on my own," the general remembered. "I had to make a living or I was going to starve to death. A young kid today does not have to make a decision at 18 anymore.

"We call them stopouts. He doesn't have to make the decision to go to work, go in the military or get out of the house. He's just stopped out; just out there -- not making any conscious decision on his future other than he's stopped off to pursue a junior college education.

"The family is so happy he has chosen to further his education, because education is the key to success, that he can live for another two years in the old man's house; maybe get a part-time job, just to keep him in pocket money. Then he may opt to go to a four-year college.

"Once he becomes 20, he loses that sense of, 'Well, I'll give the military a try.' Why should a young man with two years of college education come into the military at the age of 20? There are other factors. They're getting married younger today. He may be married, have a child."

The military's economic incentives cannot compete with other options to this 20-year-old with two years of college and perhaps a family, McMillan said.

For example, the number of two-year colleges increased from 528 in 1950 to 974 in 1975. When the enrollment of two-year programs at regular universities is added, the community-college enrollment has mushroomed from 217,000 to 4 million students over the last generation. In a sense, two objectives of the federal government are competing with each other -- billions are spent to lure young people into the military and vast sums are also spent to develop attractive alternatives in higher education.

Thus, he said, Marine recruiters are working from a greatly dimished pool as they try to sign up high school graduates "with the right attitudes, the right social mores that respond to discipline and mold them into an armed force.

"When a recruiter is working a market in which one segment doesn't respond at all and the other may respond but does not possess an over-abundance of the qualities sought by the military, it's tough. Really tough."

The general sees his recruiters caught in the middle -- denied access to juvenile records which would help screen out unfit volunteers, yet effectively prevented from recruiting many "quality" young people who see brighter futures elsewhere. These conditions he thinks, are the "seeds for fraud."

Nevertheless, he said, "If there's a commanding officer among my Marine recruiting commanders who knows that recruiting malpractice is going on and deliberately and directly told a recruiter: 'I want you to cheat to make the numbers because that's the most important thing,' I'd have to say give me his name and I'll hang him. Because I just don't believe it exists."

McMillan may be more outspoken about the draft than many other military officers who privately agree with him -- but the top manpower experts at the Defense Department insist that he and the others envision more from conscription than it could deliver.

Robert B. Pirie, Pentagon manpower chief, argues that, while the draft would obviously ease the recruiting squeeze, it would not save money -- because the armed services would then face higher turnover among soldiers trained at great expense. It might give the services more represenative proportions of rich and poor, white and black, but it would also create new differences between career troops versus conscripted, he said.

"We want the military above all to be an equal opportunity employer." Pirie said. "We want to avoid its membership being so disproportionately weighted with any racial group as to distance the military from the society it protects. We want to avoid concentrations that might make casualties politically and morally intolerable.

"We want to maintain numbers that encourage the sense that the military is racially neutral and racially integrated . . . We are in a reasonable position in those respects."

That is the official perspective at the Pentagon on the future of the all-volunteer force, but it's no secret that a lot of old soldiers like McMillan are not so optimistic.