That no man should become a father who can not and will not observe the demands of temperance in all things for the benefit of his child. CHAPTER XII. VENTILATION.--REST. _The pregnant woman breathes for two._ While pure air is desirable for all persons under every condition, it is doubly so for her. Nothing is more essential to the healthful nourishment of the fetus than that the blood be thoroughly oxygenated. Otherwise the child may be weak and feeble, and liable to disease. _Everywhere_, in railroad cars, streets, shops, public halls and dwelling houses, there is _foul air_--air that is loaded with _exhalations_ from the lungs, _emanations_ from the body, and is often vitiated by _tobacco_ and _alcohol_. Architects, builders and occupants pay but little attention to ventilation. The most important purpose of a building is evidently to keep the heat in during the winter, and keep it out in the summer. With every breath a person exhales quite a large proportion of carbonic gas, which is a deadly poison, and at the same time inhales the life-giving oxygen, constantly exhausting the supply. Yet the great fear of drafts, as well as need of economizing heat, causes most persons to breathe the same air over and over again. Gases that are inimical to health and life are constantly inhaled. If one breathed deeply and only pure air it would atone for violation of many other physiological laws. The proof of this is seen in the effects of a hunter’s or a pioneer’s life. The following from the _Lancet_ gives some practical ideas upon the ventilation of bedrooms: “If a man were deliberately to shut himself for some six or eight hours daily in a stuffy room, with closed doors and windows (the doors not being open even to change the air during the period of incarceration) and were then to complain of headache and debility, he would justly be told that his own want of intelligent foresight was the cause of his suffering. Nevertheless, the great mass of people do this every night of their lives, with no thought of their imprudence. “There are few bedrooms in which it is perfectly safe to pass the night without something more than ordinary precautions to secure an inflow of fresh air. Every sleeping apartment should, of course, have a fireplace with an open chimney, and in cold weather it is well if the grate contains a small fire, at least enough to create an upward current to carry off the vitiated air of the room. In all such cases, however, when a fire is used, it is necessary to see that the air drawn into the room comes from the outside of the house.