Since there must be a ball in each bag, it is enough to put a ball in each bag first. Every bag must have a ball.

Then you can put it as you like, and you can put it as you want.

There are 3 7 = 2187 permutations and combinations.

Oh, yes, the bag has no number, so it should be.

① Put all the rest in one bag, 1 species.

② Seven balls split in two and stacked in two bags, 162534, 3 kinds.

③ Seven balls are stacked in three bags,115124133223, four kinds.

So a * * * is 1+3+4=8 kinds.

1L positive solution!