Compounds that are not membrane permeable cause osmosis as we saw in this lab. Compounds that ARE membrane permeable themselves diffuse through the membrane and, therefore, do not cause osmosis. Formulate a hypothesis to address whether a newly-discovered compound is membrane permeable. In your hypothesis, make up a name for your compound. Remember that your hypothesis must be testable, e.g. using osmosis! Be specific: Your compound must have a name, and you must state what system you are going to test it on (it cannot just be "cells")