Every National bank must become a stockholder in the Reserve Bank of its respective district, and shall subscribe to the capital stock of the Federal Reserve Bank in a sum equal to six per centum of the paid up capital and surplus of such bank, payable as follows: One sixth on call, one sixth within three months, one sixth within six months and the remainder subject to call when deemed necessary.

State banks and Trust companies are not required to become members, membership being optional. Every shareholder of a Federal Reserve Bank shall be held responsible equally, and ratably, and not one for another, for all contracts, debts and engagements of such bank to the extent of the amount of their subscription to such stock at the par value thereof, which shall be $100.00.