What limits the maximum spacing of Nodes of Ranvier and which organisms tend to have the widest gaps?

Question

Assuming that a longer distance between gaps in the myelin sheath is beneficial for an organism due to the increased propagation speed, what is the limiting factor in determining the maximum spacing between nodes? I have previously encountered the analogy of the Nodes of Ranvier as forming a circuit between themselves and the previous node in order to pass on the action potential, which leads me into thinking that it is simply electrical resistance that is the cause however I assume the analogy is an over simplification and would be very interested in any alternatives. Also, is there a significant variation in node separation between organisms? Which organisms have the greatest gaps?

Answer 1