Section 55. This section and sections fifty-three and fifty-four shall constitute the plan of the commonwealth as required by the National Foundation on the Arts and Humanities Act of 1965 (Public Law 89–209). The council shall be the sole agency of the commonwealth for the administration of said Act. The state treasurer shall be custodian of funds received by the commonwealth under section 5 (h) of said Act, and said funds shall be expended solely by the council, without special appropriation, on projects and productions approved by it which carry out one or more of the objectives of section 5 (c) of said Act.