Shortly after Christmas, Commodity Futures Trading Commision Chairman William T. Bagley circulated a brief note to the commission's staff, with copies to the news media.

"I have now heard from California that I will not be appointed to the Appellate Court. Wanted you to know this and thus to know that I will not be leaving the chairmanship as some reports had indicated," the message said.

The end to the speculation about when or whether Bagley would leave the regulatory agency that supervises the $1-trillion-volume commodity markets clears some of the question marks out of the paths of the congressional oversight committees that will hold reauthorization hearings on the CFTC in March.

As one Senate legislative aide said this week, "Now it looks like we'll definitely be amending the (CFTC) act concerning the term of the chairman . . . once the law says the position is "at the pleasure of the President,' you may see some changes over there."

Bagley, who has been a controversial and outspoken figure during the first 30 months of his tenure, was appointed in April 1975 by then President Gerald Ford for a full term of five years. Without an amendment to the CFTC Act, congressional sources explained, Bagley would remain as chairman of the agency until April 1980. An amendment however could not prevent Bagley from continuing to serve as a commissioner through 1980, however.

While some observers point to vice chairman John V. Rainbolt II as the most likely person to be named chairman under the amendment, others disagree. Some Capitol Hill sources said the staffs of various senators on the Agriculture Committee, which has oversight responsibilities for the commission, have been asking former CFTC officials and commodity industry executives for recommendations for the post.

A highly respected lawyer who specializes in commodity and security law reportedly suggested the names of two well-known Securities and Exchange Commission attorneys, Irving Pollack and Nicholas Wolfson. Chicago Board of Trade officials forwarded the name of Philip Johnson, a Chicago attorney and one of the leading voices on the American Bar Association's commodity law and commodity options panel.

Should Bagley stay on as a commissioner, there will still be two vacancies this spring. Commissioner Read P. Dunn's three-year term expires in April, and Rainbolt, who was not formally reappointed by the President last spring when his term expired, must either be renominated or leave the agency.

These vacancies would give the White House and Congress some flexibility as they attempt to reorganize the once troubled agency.

Commission sources also noted this week that one of the most recent furors at the commission, triggered by the hiring of former Bay Area Transit System president Elmer Cooper as a $182-a-day consultant on Bagley's personal staff, is not over.

Bagley plans to change Cooper's status soon to one of full-time staff member as one of his personal aides, charged with handling consumer problems, an affirmative action program and internships for minorities.

Cooper, who resigned from his BART position in a "mutual agreement" with the other board members, had come under investigation by BART auditors and by a county grand jury for alleged irregularities in his expense account reports. For one nine-month period, Cooper's expenses ran to more than $19,000.