Soften one envelope of gelatin in 2/3 c. cold water in a small saucepan. Stir over low heat until the gelatin is dissolved. Remove from heat.
In a mixing bowl beat the cottage cheese slightly with a mixer, then stir in gelatin and the chopped green pepper and scallion.
Spread the mixture into a deep 9x13 inch pan. Chill.
Soften second envelope of gelatin in 1/4 c. cold water in small saucepan, stirring over low heat til dissolved. Remove from heat.
Flake the tuna with a fork into a large mixing bowl. Add celery, mayo, and lemon juice and toss gently to combine. Stir in gelatin.
Carefully spread the tuna mixture over the top of the cottage cheese mixture. Chill at least 2-3 hours.
Cut and serve.
NOTE: I could not find a decent photo of this recipe. It's a retro-style recipe, but it's actually very light and elegant looking, and tasty enough that the pre-schoolers at the day care center where I cooked gobbled it up, when I got tuna on the cheap!