For want of an exact code many points of etiquette are with us left open to discussion, and this without reference to foreign ideas. Thus the custom of inviting gentlemen to call when a married lady wishes to give them the entree to her house seems to have become an obsolete one with a great many. Quite recently a discussion took place as to its propriety between several ladies of distinction in this city. One lady said that it was the Philadelphia custom for gentlemen to call where they wished, without waiting for an invitation, after they had made the acquaintance of any lady in the family; and more than one married woman asserted that they had never yet asked a gentleman to come to see them; while another insisted that gentlemen generally would not venture to make a call upon any married lady unless she had invited them, or they had first asked her permission. As a difference of opinion exists on this point, it would be well if it could be an understood thing that any gentleman wishing to make the acquaintance of a lady could, after having himself presented to her, leave his card at her house with his address upon it. Of course this applies only to comparative strangers, for any young man can commit his card to his mother or sister to leave for him at a house where either visits, if he wishes to be included in invitations. Unless his card is left in this way or in person, how can he expect to be remembered? Some years ago, a lady who gave a ball during the winter after her return from a residence abroad, omitted to send invitations to the young men who, having previously visited at her house, had not left their cards at her door since her arrival home, preferring to substitute gentlemen who had never been entertained by her to inviting those who were so remiss. For this reason she gave permission to several young ladies to name gentlemen among their friends whom they would like to have invited; and so agreeable to the hostess was the selection thus made that she placed permanently upon her inviting list the names of those who sufficiently appreciated her courtesy to remember afterward the slight duties which their acceptance of her hospitality imposed upon them.