The demonstration garden products plant, the establishment of which was heretofore authorized by law, shall be continued for the purpose of teaching any citizen of West Virginia, by the demonstration method, how vegetables, berries, fruits or other garden products may be sorted, graded, processed or marketed under methods conforming to consumer demands and economically profitable to the producers. It shall be the duty of the cooperative extension service of the college of agriculture of the West Virginia University to select a location for the aforesaid demonstration plant, and after the necessary buildings and equipment shall have been provided, the demonstration shall be administered under the direction and supervision of said cooperative extension service of the college of agriculture.