Every such city, so acquiring any such cemetery lands or shares and control of such cemetery corporation or association, may likewise at the same time, or at any other time, accept and acquire by gift or donation money or funds, the income thereof, and so much of the principal as the donor may by express terms of the gift provide or permit shall be expended for the preservation, care, upkeep and adornment of such lands. Such moneys and funds for income purposes shall be invested from time to time in interest-bearing bonds of the same classes or kinds, and by the same city officials, as such city’s bond sinking funds are or may be directed by law to be invested; and the principal sums thereof, except as permitted by the donor as aforesaid, shall be preserved and kept for income purposes. If such income revenue should prove insufficient to provide for the reasonable care and upkeep of the land which, or the control of which, may be so acquired, the city shall have power to provide therefor from its general revenue.