CREATE TABLE table_54650 ("Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT)

who was the director of the episode with production code ad1a26?
SELECT "Directed by" FROM table_54650 WHERE "Production code" = 'ad1a26'
SELECT "Directed by" FROM "table_54650" WHERE "Production code" = 'ad1a26'