Sugar is soluble and increases the density of the water. Eggs will float, kind of the same way salt works, but it won't destroy your sample. I'm really not sure why they use Sugar
specifically, there are other materials that can do the same thing.
I don't like to use preservatives
, because it risks killing the specimen, and I like when things move.
I recommend distilled water. Vinegar should work well as a temporary preservative. Shroom