§ Every citizen is liable between his seventeenth and sixtieth year to render in time of war personal service in defence of the Union, and he is liable to undergo a course of peace training for military service, and may be required to commence that training in his twenty-first year, and to complete it not later than his twenty-fifth year; but he may voluntarily commence it in any year between his seventeenth and twenty-first year. Of the total number liable to peace training, only 50 per cent. shall actually undergo the training unless special financial provision is made by Parliament otherwise. But every citizen liable to training who has not been entered in his twenty-first year must serve as member of a rifle association from his twenty-first year for four consecutive years.