After the famous discovery of Alessandro Volta of the “Volta pile” reported in:

Alessandro Volta, On the Electricity Excited by the Mere Contact of Conducting Substances of Different Kinds (in French: http://knowledge.electrochem.org/estir/hist/hist-01-Volta-1.pdf ) Philosophical Transactions of the Royal Society of London, Vol. 90, pp 403-431, 1800. (partial English translation: http://knowledge.electrochem.org/estir/hist/hist-20-Volta-2.pdf ) electrochemical power sources were born. Volta used “a sufficient number of metallic arcs or bows, one arm of which is of silver, or copper plated with silver, and the other of zinc” immersed in saline solution to obtain electricity.

I was always wondering what are the reactions in a Volta pile? Normally zinc is anode and dissolves (oxidized):

Zn = Zn2+ + 2e

But what is the cathodic (reduction) reaction on silver.

Oxygen reduction is the main candidate

O2 + 2H2O + 4e = 4OH-

or any other opinion?