The University may by Statute determine in respect of each of the Professorships specified in the said Schedule (other than the Professorship of Political Economy and the Sherard Professorship of Botany) how and by whom upon the Occasion of the next or any subsequent Avoidance of such Professorship the Professor is to be elected, and in the Case of the Sherard Professorship of Botany therein named the Professor shall be appointed by the President and Council for the Time being of the Royal College of Physicians of London ; and the said University may, with Consent of the said President and Council of the College of Physicians, vary and define the Qualifications of Candidates for Election to the said Sherard Professorship.