Filling of casual vacancies

All casual vacancies among the members (other than ex-officio members) of any authority or other body of the Institute shall be filled, as soon as may be convenient, by the person or body who appoints, elects or co-opts the members whose place has become vacant and any person appointed, elected or co-opted to a casual vacancy shall be a member of such authority or body for the residue of the term for which the person whose place he fills, would have been a member.