Section 16A. The trustees shall establish and maintain at said station a diagnostic laboratory for the purpose of the provisions of clause First of section seventeen relative to domestic animals. Experiments may be conducted at said station in co-operation with Massachusetts dairy farmers to control and eliminate the disease of mastitis. For the purpose of the collection and laboratory examination of milk samples to eliminate mastitis, in the conduct of such work, a fee as determined annually by the commissioner of administration under the provision of section three B of chapter seven for each sample tested may be charged. The director shall accept samples of milk for test collected by the department of agriculture and may accept samples from such other qualified persons as he may approve for the collection of such samples.