Transistors

[Terry]

Just to clarify this "holes" business ...

You seem to overlook the fact that electron flow in electrical and electronic circuits had been well understood for a very long time before  the invention and development of the transistor but nobody ever mentioned anything about 'holes' ...

Yet you seem to be saying that you can't understand how an electric current flows through any circuit without expressing it in terms of holes ...

Forget all about your multi-coloured marbles and just concentrate on the electrons that are free to move. The simplest way is with a row of 2p pieces - it was old ha'pennies when I saw this done!
Get two rulers and place them either side of the row of coins, arranged at right angles to the edge of a desk and with the first coin 2" or a little less from the edge.

Place another coin on the edge so that it is overhanging - like shove ha'penny - then hit it sharply with the heel of the hand. The coin will hit the first one in the row and a coin at the other end pops out.

Voilà! A practical demonstration of electron flow and not a hole in sight!