Evidence respecting handwriting may be given by experts, by comparison, or by comparison by the jury, with writings of the same person which are proved to be genuine. [C51, §2404; R60, §3997; C73, §3655; C97, §4620; C24, 27, 31, 35, 39, § 11278; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §622.25 ]