All employes appointed by the President pro tempore shall be under the direction and control of the President pro tempore who shall assign them to such duties as are usually performed in the positions to which they have been respectively elected or appointed. The President pro tempore may transfer any of such employes, appointed by him from one position to another position in order best to bring about efficiency and a more equal distribution of the work of the Senate. All other employes of the Senate shall be under the direction and control of the officer by whom they were appointed.