If any of the directors at any time subsequent to his election accept or continue to hold any other office or place of trust or profit under the company, or be either directly or indirectly concerned in any contract with the company, or participate in any manner in the profits of any work to be done for the company, or if such director at any time cease to be a holder of the prescribed number of shares in the company, then in any of the cases aforesaid the office of such director shall become vacant, and thenceforth he shall cease from voting or acting as a director.