Section 91. Every person, before engaging in the practice of chiropractic in this commonwealth, shall make application to the board, on a form prescribed and furnished by it, for a certificate to practice chiropractic. Said application shall be filed with the secretary of the board at least thirty days before the date of examination, and shall be accompanied by an examination fee as determined annually by the commissioner of administration under the provision of section three B of chapter seven or, in the case of reexamination, each applicant shall pay a fee as determined under the aforementioned provision for each subject upon which he is reexamined. Each applicant must be at least eighteen years of age and of good moral character, and shall furnish the board with satisfactory proof that he has completed two years in a curriculum leading to a bachelor’s degree in liberal arts or science and that he is a graduate of a chiropractic school or college approved by the board, and which is (1) authorized by its charter to confer the degree of doctor of chiropractic; (2) gives a course of four academic years, comprising a total of four thousand hours, to matriculants possessing the educational qualifications required for graduation from an accredited public high school; and (3) confers such degree only after personal attendance of the applicant therefor at such course, and upon completion thereof.