The members of the House of Representatives shall be apportioned among the several counties, according to the number of population in each, as nearly as may be, on a ratio obtained by dividing the population of the State, as ascertained by the most recent United States census, by the number of members of which the House is composed; provided, that whenever a single county has sufficient population to be entitled to a Representative, such county shall be formed into a separate Representative District, and when two or more counties are required to make up the ratio of representation, such counties shall be contiguous to each other; and when any one county has more than sufficient population to be entitled to one or more representatives, such representative or representatives shall be apportioned to such county, and for any surplus of population it may be joined in a Representative District with any other contiguous county or counties.