  Parallel and series nucleation are the basic elements of the complex
nucleation process when two saddle points exist on the free-energy landscape.
It is pointed out that the nucleation rates follow formulas similar to those of
parallel and series connection of resistors or conductors in an electric
circuit. Necessary formulas to calculate individual nucleation rates at the
saddle points and the total nucleation rate are summarized and the extension to
the more complex nucleation process is suggested.
