(3) " business" includes any trade, commerce or manufacture, or any adventure in the nature of trade, commerce or manufacture, or any profession or vocation the profits of which are chargeable according to the provisions of section 10 of the Indian Income- tax Act, 1922 : Provided that where the functions of a company or of a society incorporated by or under any enactment consist wholly or mainly in the holding of investments or other property, the holding of the investments or property shall be deemed for the purposes of this definition to be a business carried on by such company or society: Provided further that all businesses to which this Act applies carried on by the same person shall be treated as one business for the purposes of this act;