Armed with a signal from two Wall Street gurus, institutional investors went on a selling spree today that brought the Dow Jones industrial average down by almost 22 points.

The signal came from two investment experts at Morgan Stanley & Co. Inc., Barton M. Biggs and John A. Mendelson, who told salesmen at an early-morning meeting that they had lost their enthusiasm for stocks for the time being. "I am inclined to be considerably more cautious about fresh buying," Biggs told clients in his regular Monday research paper.

That caution led Biggs, one of Wall Street's most carefully watched market pickers, to drop six stocks from the firm's "buy" list, while retaining seven other selections. Biggs suggested that investors not sell "quality" big-name stocks, but instead "sell secondary, speculative names where the buying has been overenthusiastic."

The stocks dropped from the list were Delta Airlines, General Electric, International Business Machines, Johnson & Johnson, and Union Camp, while Biggs retained American Telephone & Telegraph, Eastman Kodak, Federal National Mortgage Association, General Re Corp., Gillette, Eli Lilly and Philip Morris.

In Biggs' view, however, the eight-month stock binge that has seen the market set continuing records does not appear to have ended, although he told investors today that it may be "close to the end of the beginning." In other words, as Biggs put it in the title of his Monday report, "A Slight Case of Acrophobia," the "bull market" is nearing the end of what may be the first of a series of upward moves.

But other market analysts discounted Biggs' view and said it is unlikely that today's selling would lead to a broader market "correction" or downward move. "There is no correction," said Charles Lewis, a Shearson/American Express vice president. "Each group in the market has already corrected itself."

Lew Smith, a market analyst at Bear, Stearns & Co., said the fall in the industrial average came "because the crowd felt compelled to make a decision. Usually when the herd does something, it is wrong. I see little major selling ahead, but worried portfolio managers can make a rebound difficult," Smith added.

Even with the institutional selling, volume on the New York Stock Exchange fell from 105.7 million shares Friday to 88.3 million today, as the Dow industrials dropped to 1204.33, with 578 stocks gaining and 1,117 declining. The New York Stock Exchange index fell 1.23 points to 93.04, and the average price per share dropped 43 cents.

Of the widely traded stocks, oil stocks showed some gains, with Gulf Oil up 3/8 to 33 7/8 and Exxon up 3/8 to 35 3/4. But IBM lost 2 to 115, Eastman Kodak fell 1 1/2 to 83 3/8, and General Electric fell by 2 7/8 to close at 109.