In the trial of all indictments, complaints, or other proceedings against persons charged with the commission of crimes, offenses or misdemeanors, the person so charged is, at his own request, but not otherwise, a competent witness, and his failure to make such request shall not create any presumption against him. But every such person examined as a witness shall be subject to cross-examination as other witnesses. Except as above provided, nothing in this section shall render any person, who in any criminal proceeding is charged with the commission of a criminal offense, competent or compellable to give evidence against himself, nor render any person compellable to answer any question tending to criminate himself. (1856-7, c. 23; 1866, c. 43, s. 3; 1868-9, c. 209, s. 4; 1881, c. 89, s. 3; c. 110, ss. 2, 3; Code ss. 1353, 1354; Rev., ss. 1634, 1635; C.S., s. 1799.)