Executives of McCormick & Company and Sandoz Ltd. yesterday agreed to hold another meeting to discuss a merger, but an exchange of nasty letters between executives of the two companies indicated they are far from an agreement.

Sandoz asked for the second session after complaining that McCormick oficials had not given serious consideration to their offer to buy the Baltimore spice company for $418 million -- $37 a share.

In a letter released yesterday morning, McCormick Chairman Harry K. Wells said he would be willing to meet again "if you have anything additional to add."

Wells told sandoz Chairman Yves Dunant he "takes strong exception" to Dunant's charge that the interest of McCormick's management and board of directors might conflict with the needs of the stockholders.

"Our company's policy of independence will not stand in the way of due deliberation" of the offer, added Wells.

Later in the day Sandoz released a response from Dunant to Wells, asking for a meeting at 9 a.m. Monday. Duant complained that when the two met Tuesday, Wells seemed adament about keeping McCormick an independent company "at any and all cost."

"Your mentioning litigation, managerial defection and a fight to the bitter end could hardly have led us to any other conclusion," said Dunant.

Dunant himself made similar threats on Wednesday, warning that McCormick executives could get in legal trouble with shareholders and the Securities and Exchange Commission if they flatly rejected the Sandoz bid.