No satisfactory means exist for determining to what extent a continuance of the importation of slaves was necessary, in an economical point of view, to the States of North Carolina, South Carolina, and Georgia. There is some reason to suppose that the natural increase of the slave population in Virginia at that period more than supplied her wants; and perhaps the less healthy regions of the more southern States may have still required foreign supplies in order to keep the lands already occupied under cultivation, or to make new lands productive.[214] All that is historically certain on this subject is, that the representatives of the three most southerly States acted upon the belief, that their constituents would not surrender the right to continue the importation of slaves, although they might, if left to themselves, discontinue the practice at some future time. These declarations, however, had not been made at the time when the principles on which the Constitution was to be framed were sent to the committee of detail. Nothing had yet occurred in the Convention, to make it certain that the power to import would be retained by any of the States. The committee of detail had, therefore, so far as the action of the Convention had gone, an unrestricted choice between a full and a limited commercial power. They consisted of three members from non-slaveholding and two from slaveholding States;[215] but as one of them, Mr. Rutledge of South Carolina, was one of the persons who subsequently announced to the Convention the position that would be taken by his own State and by North Carolina and Georgia, there can be no doubt that he announced the same determination in the committee. In their report, they shaped the commercial power accordingly. They provided that the legislature of the United States should have power to lay and collect taxes, duties, imposts, and excises; and to regulate commerce with foreign nations, and among the several States. But they also reported several restrictions upon both the revenue and commercial powers. Besides providing, in accordance with the ninth resolution adopted by the Convention, that direct taxation should be proportioned among the States according to the census, to be taken by a particular rule, they added the further restrictions, that no tax or duty should be laid by the national legislature on articles exported from any State, nor on the migration or importation of such persons as the several States might think proper to admit; that such migration or importation should not be prohibited; that no capitation tax should be laid, unless in proportion to the census; and that no navigation act should be passed without the assent of two thirds of the members present in each house.