A Swiss company that purchased nearly 5 percent of McCormick & Co.'s nonvoting stock last October has made an offer to buy the Baltimore-based spice company at $37 a share.

Although the chairman of Sandoz Ltd., of Basle, is expected to accept an invitation to meet with McCormick's board next Wednesday, McCormick emphasized its policy of independence in announcing the offer yesterday.

"There should be no inference or expectation that there will be any transaction," McCormick Chairman Harry K. Wells said.

McCormick announced last Oct. 15 that Sandoz had acquired 4.8 percent of its nonvoting stock before Sept. 19. Four days later the Baltimore company said it was "determined not to become part of Sandoz' although the Swiss company hadn't made an offer for McCormick.

Early in November, Wells sent Sandoz Chairman Dr. Y. Dunant a letter accusing Sandoz' American representatives of purposely disrupting the trading of McCormick stock and generating takeovers rumors.

One McCormick official, who didn't want to be indentified, said several companies had volunteered to make friendly offers for McCormick to prevent a takeover by Sandoz, but were turned down.

The American representative is Sandoz United States Inc., a holding company for the Swiss parent's several U.S. companies. These include Northrup-King, a seed company, and other companies that manufacture and distribute Ovaltine, dyestuffs and other chemicals, and the main business in this country -- prescription pharmaceuticals.

McCormick shares opened at 29 and closed at 27 1/2 bid, 28 ask on a volume of 254,085 shares on the over-the-counter market. Wednesday's close had been 22 3/4 bid, 23 1/4 ask, and Monday and Tuesday volume had totaled 150,000 shares. Before Sandoz' purchase of McCormick stock was announced last fall, the price was in the range of 17 to 19, a McCormick spokesman said.