Every corporation, which on March 10, 1917, was actually and publicly engaged in banking or trust business in this state in full compliance with the laws hereof, which were in force immediately prior to March 10, 1917, may, if it otherwise complies with the provisions of this title, continue its said business, subject to the terms and regulations hereof and without amending its articles of incorporation, although its name and the amount of its capital stock, the number or length of terms of its directors or the form of its articles of incorporation do not comply with the requirements of this title: PROVIDED,

(1) That any such bank, which was by the director lawfully permitted to operate, although its capital stock was not fully paid in, shall pay in the balance of its capital stock at such times and in such amounts as the director may require;

(2) That, except with written permission of the director, any bank which shall amend its articles of incorporation must in such event comply with all the requirements of this title.