" The material part of section 24 runs thus : "24.(1) Where any assessee sustains a loss of profits or gains in any year under any of the heads mentioned in section 6, he shall be entitled to have the amount of the loss set off against his income, profits or gains under any other head in that year * * * * * Provided that in computing the profits and gains chargeable under the head "Profits and Gains of business, profession or vocation", any loss sustained in speculative transaction which are in the nature of a business shall not be taken into account except to the extent of the amount of profits and gains, if any, in any other business consisting of speculative transactions * * * * * (2) Where any assessee sustains a loss of profits or gains in any year, being a previous year not earlier than the previous year for the assessment for the year ending on the 31st day of March 1940, in any business, profession or vocation, and the loss cannot be wholly set off under sub section (1), so much of the loss as is not so set off or the whole loss where the assessee bad no other head of income shall be carried forward to the following year, and (i) where the loss was sustained by him in a business consisting of speculative transactions, it shall be set off only against the profits and gains, if any, of any business in speculative transaction carried on by him in that year; (ii) where the loss was sustained by him in any other business, profession or vocation, it shall be set off against the profits and gains, if any, of any business, profession or vocation carried on by him in that year pro 702 vided that the business, profession or vocation in which the loss was originally sustained continued to be carried on by him in that year; and (iii) if the loss in either case cannot be wholly so set off, the amount of loss not so set off shall be carried forward to the following year and so on. * * * * * * 2A.