Section 24. The directors of a company shall be jointly and severally liable, to the extent of its capital stock, for all its debts and contracts, until the whole amount of its capital stock as originally fixed by its agreement of association, or if a chartered company, by its directors, and authorized by the department, shall have been paid in, and until a certificate stating the amount thereof so fixed and paid in shall have been signed and sworn to by its president, treasurer, clerk and a majority of its directors, and filed in the office of the state secretary.