Can an insured change the beneficiary of a life insurance policy to his wife?

In Nally v. Nally, 74 Ga. 669, 58 Am. Rep. 458, an unmarried man took out a policy of insurance on his life, one condition of which was that the policy was issued and accepted upon the express condition that the assured might, with the consent of the company, at any time, assign it, or, before assignment, change the beneficiaries, or make any other change. The person named as the beneficiary was the sister of the assured, and to her he delivered the policy, and paid the premiums to that time. Subsequently he married, and, as an inducement thereto, he agreed that, if the woman would marry him, she should be made the beneficiary of the policy. After the marriage, and when the next semiannual premium fell due, the assured paid it, on condition that the beneficiary should be changed from his sister to his wife. The sister had the policy, and would not give it up. The agent was uncertain whether the change could be made without the policy, but promised to notify the company, and have the change made if possible. The officers agreed to attend to the matter, but overlooked it. After the death of the assured, the company filed a bill to require the wife and sister to interplead, and have the question determined as to who was entitled to the money. It was held that the gift to the sister was not perfected, so as to be absolute and irrevocable, and the assured had the right to change the beneficiary of the policy, and whether such change was to be effected by parol or in writing was a matter