Profits of the Marriott Corp., a Bethesda hotel and restaurant firm, jumped 24 percent on a sales of gain of 12 percent in the third fiscal quarter ended May 5, President J. W. Marriott Jr. announced yesterday.

Earnings in the recent 12-week period were $11.63 million (32 cents a share) compared with $9.37 million (26 cents) in the same period a year earlier, as sales increased to $269 million from $240 million.

A Marriott amusement park in California operated with an expected loss in the quarter but particularly strong business was reported for hotels, eating establishments and the Sun Line cruise ship operation.

"Early-season results at our California theme park and a decline in contract food services limited operating profits to a modest increase for the quarter," Marriott stated.

Still, combined with results for earlier months, Marriott's nine-month profits were up 26 percent to $31.38 million (86 cents a share) from $24.87 million (68 cents) a year ago. Sales for the three quarters rose 14 percent to $858 million.

Marriott sold its automatic food service division here to Wometco Enterprises in the recent quarter as well as some land adjacent to its California park, at Santa Clara. In addition, the company wrote off its investment to date in a once-planned park for the metropolitan Washington area.

Plans for a park in Northern Virginia have been abandoned and no site has been found in Maryland. The area park costs written off were $2 million in the previous quarter, the company declined to state the amount of theme park writeoff in the recent period.

The net result of extraordinary gains and losses in the third quarter was a one-time improvement in earning equal to about 2 cents a share, Marriott said in a statement.

"Operating profit gains in the fourth quarter should be excellent, with especially, strong performances by theme parks and hotels. The year as a whole will be another record-setter," Marriott added.

A spokeswoman said a final decision on the area theme park probably won't be made until about Christmas.

American Realty Trust, an Arlington-based real estate investment trust, reported profits of $952,321 (43 cents a share) in the first fiscal six months ended March 31, reflecting gains of $981,495 from selling properties. In the same period a year earlier, ART lost $204,760. Revenues dipped to $2.52 million from $2.7 million.

The trust reported a net loss of $353,948 in the same quarter compared with loss of $412,321 last year. Chairman Thomas J. Broyhill said severe weather had an adverse impact on ART hotels and motels in the traditionally weak season and forecast an improved showing in the next six months.