Biochemist William H. Frey, arguably the world's principal authority on human tears, has a few things to say about political crying in general and Pat Schroeder's crying last week in particular. "In the first place," he says, "it has nothing to do with sex. It has to do with humanity. Only humans weep emotional tears. And in my view, there are times for even a politician to act like a human being.

"The issue is really one of how we perceive crying and what is the response of the American electorate to crying -- whether it is a male or female who is doing the crying. Sometimes it is accepted by the public when a man cries and sometimes it is not."

Women do cry about four times as much as men, Frey says, but that, in his view, is little more than a biochemical phenomenon.

Frey is director of the Psychiatry Research Laboratories at St. Paul-Ramsey Medical Center in St. Paul, Minn., specializing in the biochemistry of the human brain. This includes work on Alzheimer's disease and other dementias, but it also includes research on emotional crying and the content of tears. Much of Frey's research is included in his 1985 book, "Crying: The Mystery of Tears."

Still, whatever the biochemistry, Frey acknowledges the psychological and social aspects in the public reactions to public tears.

"My feeling," he said after Schroeder tearfully announced her decision not to run for president, "is that people have to realize that emotional crying is a natural part of being human, and I guess I feel that this is something that should be accepted. Obviously, if Pat Schroeder or, say, Lyndon Johnson broke down into tears every time they were interviewed or somebody said a cross word about them, well, there would be a problem. But that is not what we're dealing with here -- with Pat Schroeder or Edmund Muskie or any of the others {who have cried in public}.

Women, Frey's work has suggested, are biochemically predisposed to cry, and that tendency may be related to certain hormones. The research has also suggested, but not yet proven, that crying may be physically beneficial, a way of ridding the body of excess stress chemicals.

The emotional benefits, of course, of "having a good cry" are well known.

Hippocrates described tears as "humors from the brain." Not for the first time by any means, Hippocrates was probably right. Some tears, those induced by emotion, do appear to contain certain brain chemicals -- the protein messengers between nerve cells known as neurotransmitters or neuropeptides, and some other hormones known to be related to stress, especially prolactin and ACTH (adrenocorticotropin hormone.)

It is known that perceptions and emotions can induce the secretion in the brain of some of these chemicals, which have a variety of functions -- turning this hormone on, that one off, constricting or dilating blood vessels, alleviating pain, increasing or decreasing alertness, promoting or inhibiting sleep, whatever the brain/mind deems suitable. They are found elsewhere in the body as well, with a myriad of other functions, still not completely understood.

Frey has identified the hormone prolactin as a likely major player in the formation of the tear glands and in the increased crying in women over about the age of 18. There is, however, no difference in the amount of prolactin in boys and girls under 12, an age at which one's tendency to cry seems unrelated to sex.

Prolactin, he notes, develops to a 60 percent higher level in women between the ages of 12 and 18, and as its name suggests, its key role is to promote lactation.

Experiments on sea birds like gulls and cormorants have shown that their tear glands tend to excrete much of the excess salt that they consume during long periods over the ocean. Their tears, notes Frey, are "much, much saltier" than human tears and, moreover, scientsts have found that the glands may be stimulated by prolactin.

Furthermore, dopamine, the chemical deficient in people suffering from Parkinson's disease, is known to inhibit the release of prolactin. Some people who suffer from a disorder involving excessive crying have been successfully treated with L-Dopa, a drug found useful in treating Parkinson's disease, Frey said.

If crying is so natural -- indeed, a reaction to body chemistry -- then why is there a flap every time a politician cries in public?

"The trouble is," says Dr. David Rubinow, newly named clinical director of the National Institute of Mental Health, "crying and the expression of emotion in as overt a fashion as Pat Schroeder's is equated in our society with weakness or loss of control. If somebody is in a position of leadership, then you want them to be in control.

"In this society, in terms of stereotypes, you have the sort of 'good' masculine qualities and the 'not so good' feminine qualities that society seems to have defined. It's a chicken-and-the-egg situation . . . It is unclear whether people view women as being weak because they express their feelings or people view expressing your feelings as being weak because it is more feminine."

But "wanting to see someone in control all the time," says Rubinow, who is a psychiatrist, "fails to take into account that somebody who does not express the emotions they are having, irrespective of how strong they are, may be operating in such a way as to compartmentalize most of their experiences and responses. They may thus wind up suffing a number of conceptual and emotional blind spots.

"In a way, if you want someone to make an informed decision, you'd be better off having someone who is aware of their emotional response and is able to factor it into the decision-making process, rather than someone whose feelings may be more subtly and insidiously influencing their decisions."

Frey sees the reaction in a more political sense: "The real question, I think, is do wewant a president or national leaders in general who are masters of deception and of hiding their own true feelings and their real agendas, or do we want leaders who are open and honest and forthright about their feelings? I think a lot of Americans feel that in order to deal with our adversaries effectively, we need leaders who are masters of deception. But my own feeling is that we should wholeheartedly endorse genuine displays of feelings when they are appropriate, as they were in this case."

"A lot that goes into it is cultural," Rubinow said. "I mean, even something as simple as in Europe, when you greet somebody you greet them by kissing them. Well, men don't kiss each other in our society and that would be -- well, you know people would have a very funny response if, when Ronald Reagan met George Bush, they kissed each other. It's a measure of the beliefs that are prevalent and how those beliefs and customs dovetail with existing stereotypes about the desirability of so-called masculine and feminine traits."