Lurching for a third day through the bone-dry chaparral of the Santa Cruz Mountains, the Loma Fire by Wednesday morning had grown in size by 10 percent, a sizzling 2,250-acre blaze with 300 homes in its path and more than 1,000 firefighters trying to rein it in. The human force fighting the Loma had doubled in size since Tuesday afternoon, reaching 1,092 by sunup, with fresh crews stepping in at 9 a.m. to relieve firefighters from around the region who had worked through the night.