Dissolve gelatin and salt in boiling water. Stir in lemon juice.Drain pears,reserving syrup.Measure syrup,add enough cold water to make 1 1/2 cups and stir into gelatin.Pour half the gelatin into bowl and chill until thickened. Dice pears and fold into thickened gelatin and spoon mixture into 1 1/2 quart mold. Chill until set,but not firm. Meanwhile,chill remaining half of gelatin mixture until slightly thickened.Soften cream cheese in large bowl.Gradually blend in slightly thicken gelatin and ginger,beating with a hand mixer until fluffy and thickened.Stir in nuts.Spoon over set gelatin in mold and chill until firm. Unmold and garnish with salad greens,optional.