Perhaps this may be the proper place to say that there are more reasons than one--and some of them are of a moral nature, too--why a child should continue to sleep alone, after it leaves the nursery. Nor is it sufficient to prohibit its sleeping with younger persons, and yet crowd it into the bed with an aged grandfather or grandmother, or with both. There is no excuse for a course like this, except the iron hand of necessity. And even then, I should prefer to have a child of mine sleep on the hard floor, at least during the summer season, rather than with an aged person. Let it not be supposed I have imbibed the fashionable idea that it is _peculiarly_ unhealthy for the young to sleep with the old. I know this doctrine has many learned advocates. And yet I doubt its correctness. I believe that the manners and habits of the old may injure the young who sleep with them, and I know that they render the air impure, like other people. But I cannot see why the mere circumstance of their being _old_ should be a source of unhealthiness to their younger bed-fellows. Still I say, that there are reasons enough against the practice I am opposing, without this. Some parents allow dogs and cats to sleep with children. Others have a prejudice against cats, but not against dogs. The truth is, that they both contaminate the air by respiration and perspiration, in the same manner that adults do. And aside from the fact that they are often infested by lice and other insects, and addicted to uncleanly habits, they ought always to be excluded, and with iron bars and bolts, if necessary, from the beds of children. But of this, too, I have treated elsewhere. SEC. 3. _Purity of the Air._ The general importance of pure air has been mentioned. I have spoken of the elements of the atmosphere in which we live, of the manner in which it may be vitiated, and the consequences to health. I have shown--perhaps at sufficient length--the impropriety of washing, drying, and ironing clothes in the room where a child is kept; of cooking in the room, especially on a stove; of suffering the floor or clothes, particularly those of the child, to remain long wet, in the room; of smoking tobacco, using spirits, burning oil with too long a wick, &c. All which has thus been said of the purity of the air of the nursery generally, is applicable to that of all sleeping rooms. It is an important point gained, when we can secure a nursery with folding doors in the centre, so as, when we please, to make two rooms of it. In that case, the division in which the bed is, can be completely ventilated a little before night, and thus be comparatively pure for the reception of both the mother and the child.