An inheritance tax in general is a tax on the exercise of a right. It is in the nature of an excise tax. Knowlton v. Moore, 178 U. S. 41. In recent years many states, as well as the federal government, have extended their taxing activities in this field. 4 COOLY, TAXATION, 4th ed. p. 3439. New York passed a statute in 1892 taxing the exercise of a power of appointment. The statute declared that whenever any person exercises a power of appointment, such appointment when made shall be deemed a transfer taxable as though the property belonged absolutely to the donee of the power and had been bequeathed or devised by such donee. This statute has been copied by several other states including Massachusetts, Rhode Island, California, and North Carolina. In interpreting and applying the statute considerable controversy has arisen as to its constitutionality. The basis for this controversy is the nature of a power, the question being whether the exercise of the power is sufficient to give the state a taxing jurisdiction.