Section 24. A person who desires to do business as a pharmacist shall, upon payment of a fee, as determined annually by the commissioner of administration under the provision of section three B of chapter seven, to the board of registration in pharmacy, herein and in sections 25 to 42D, inclusive, called the board, be entitled to examination; provided, that he shall have been graduated from a school or college of pharmacy approved by the board. If any such person is found qualified on examination, he shall be registered as a pharmacist, and shall receive a certificate signed by the president and secretary of the board. Any person failing to pass such examination shall upon request be re-examined, after the expiration of three months, at any regular meeting of the board, upon payment of a fee determined under the aforementioned provision. The board may grant certificates of registration as assistants after examination upon the terms above named, and such certificates shall entitle the holder thereof to all the privileges of a registered pharmacist during the temporary absence of the latter, which absence shall be not more than six hours in any one period of twenty-four consecutive hours; provided, that, upon application to the board, such an assistant may be permitted to exercise the privileges of a registered pharmacist for such further period as the board shall determine. No such certificate as assistant shall allow the holder thereof to engage in the drug business on his own account or as a manager to conduct a pharmacy or drug store. The board may grant certificates of registration to such persons as shall furnish with their applications satisfactory proof that they have been registered by examination in some other state; provided, that such other state shall require a degree of competency equal to that required of applicants in this commonwealth. Every such applicant for registration as a registered pharmacist shall pay to the secretary of the board a fee determined under the aforementioned chapter seven provision at the time of filing his application. No such certificate shall be granted until the person applying therefor shall have signified his intention of acting under the same in this commonwealth.