Green Salad for a Crowd

1 head Bibb lettuce
1 head Boston lettuce
1 head iceberg lettuce
1 bunch fresh spinach
1 bunch escarole
1 bunch endive
1 cup vegetable oil
1/2 cup cider vinegar
6 tablespoons sugar
2 to 4 tablespoons finely chopped onion
1 teaspoon dry mustard

1 teaspoon celery seed
3 ounces crumbled blue cheese
1/2 pound sliced bacon, cooked till very crisp and crumbled

Rinse all greens very thoroughly and drain well. Tear all greens into bite-sized pieces then toss in a large salad bowl. Chill in refrigerator. To make the dressing combine oil, vinegar, sugar, onion, mustard and celery seed in a blender, blend well. Right before serving add the blue cheese crumbles and bacon to the top of the greens, pour the dressing over all and toss gently. Serves about 20.