No export duties shall be levied or collected on exports from Puerto Rico , but taxes and assessments on property, income taxes, internal revenue, and license fees, and royalties for franchises, privileges, and concessions may be imposed for the purposes of the insular and municipal governments, respectively, as may be provided and defined by the Legislature of Puerto Rico ; and when necessary to anticipate taxes and revenues, bonds and other obligations may be issued by Puerto Rico or any municipal government therein as may be provided by law, and to protect the public credit. (Mar. 2, 1917, ch. 145, § 3, 39 Stat. 953 ; Feb. 3, 1921, ch. 34, § 2, 41 Stat. 1096 ; Mar. 4, 1927, ch. 503, § 1, 44 Stat. 1418 ; Aug. 26, 1937, ch. 831, 50 Stat. 843 .) Editorial Notes Codification Section is comprised of first part of section 3 of act Mar. 2, 1917 , down to the proviso clause. The remainder of section 3 is classified to sections 741a and 745 of this title. Prior Provisions Provisions similar to those in this section were contained in act Apr. 12, 1900, ch. 191, § 38, 31 Stat. 86 . Amendments 1937—Act Aug. 26, 1937 , reenacted section without substantive change. 1927—Act Mar. 4, 1927 , inserted imposition of income taxes. 1921—Act Feb. 3, 1921 , reenacted section without change.