(b) except in special cases provided by rules under this Act, divide the sample then and there into three parts and mark and seal or fasten up each part in such a manner as its nature permits and take the signature or thumb impression of the person from whom the sample has been taken in such place and in such manner as may be prescribed: Provided that where such person refuses to sign or put his thumb impression the food inspector shall call upon one or more witnesses and take his or their signatures or thumb impressions, as the case may be, in lieu of the signature or thumb impression of such person;