[The following will explain the third head note: Gordon was indicted for an assault with intent to murder, committed on one Green. In the prisoner’s statement he claimed that an improper intimacy had existed between his wife and Green; that upon his interfering between them, the latter made an assault upon him, in which his wife took part, and struck him upon the head with a heavy bar, used for closing a door, making a scar. The defendant then voluntarily exhibited the scar on his head to the jury. At' the close of the statement, the court, over objection of defendant’s counsel, allowed a physician to examine the scar and testify that in his opinion it was the result of an old wound and not of a recent blow.]