Mahlon Pitney, Royster Guano Company v. Virginia…
“ But no ground is suggested, nor can we conceive of any, sustaining this exemption which does not apply with equal or greater force as a ground for exempting from taxation the income of Virginia corporations derived from sources without the state where they also transact income-producing business within the state. Corporations of this class derive no more protection from the state of their origin with respect to their outside business, and are no less subject to taxation by the states in which such business is conducted, than corporations of the other class ”
