: If a person is found to be in possession of any narcotic drug, or if evidence is found that marijuana, opium, or coca is being cultivated on the land cultivated by him, or if any substance is found that has undergone some process required for the manufacture or production of any narcotic drug. Or if it is found that after the production of narcotic drugs from a substance, some remnants of that substance are kept with him, he shall submit evidence that such substance was obtained or kept by him in accordance with this Act and the rules or orders issued under this Act. Unless such evidence can be presented and proven otherwise, he will be deemed to have committed an offense punishable under this Act.