Macromolecular cytosolic delivery: Cell membranes as the primary obstacle

The "evolution" of a thing, a custom, an organ is thus by no means its prog ressus toward a goal, even less a logical progressus by the shortest route and with the least expenditure of force, but a succession of more or less p rofound, mutually independent processes of subduing, plus the resistances t hey encounter, the attempts at transformation for the purpose of defense an d reaction, and the results of successful counteractions. The form is fluid , but the "meaning" is even more so (Friedrich W. Nietzsche).