permanent total disablement

means such disablement of a permanent nature as incapacitates an employee for all work which he was capable of performing at the time of the accident resulting in such disablement: Provided that permanent total disablement shall be deemed to result from every injury specified in Part I of the Fourth Schedule or from any combination of injuries specified in Part II thereof where the aggregate percentage of the loss of earning capacity, as specified in the said Part II against those injuries, amounts to one hundred per cent.