§ 38. Subjects to be acted upon. At an extraordinary session of the legislature convened pursuant to the provisions of this article, no subject may be acted upon except such as may be specified in the perfected joint or concurring petition pursuant to which such session is convened, or such as may be specified in any perfected joint or concurring petition received by the temporary president and the speaker prior to or during such extraordinary session, or such as may be added to such petition or petitions by amendment thereof by joint resolution adopted by two-thirds of the members elected to each house.