1. (1) The case in which ψ(n) tends to zero may be omitted, for in this case f(x) does not converge.
2. (2) Izumi, this Journal, 4 (1926).
3. (2) Narumi, this Journal, 4 (1926).
4. (3) Narumi, the foregoing paper.
5. (4) Izumi, this Journal, 4 (1926).