It goes without saying that sleeping rooms should always be thoroughly ventilated. The occupant should take care that he does not lie in a direct draught from a window or door, because it has been found by experience that one is less likely to catch cold if he sleeps out of doors than he is if he sleeps in a direct draught from a window or door. Just why this is has not been satisfactorily accounted for, but the fact remains. So if you must sleep in the house, secure perfect ventilation without direct draughts. 5. THE CONTROL OF THE THOUGHTS. There is no more effective safeguard for the man who wishes to lead a continent life than the control of the thoughts. It goes without saying that the man who thinks about sexual matters, especially the one whose imagination runs wild upon all kinds of sexually stimulating images, is only inviting temptation to relax his continence. If he controls his thoughts during those times when he is less amenable to temptation, he is far more likely to be able to control his acts at those times when his physical condition makes him most amenable to temptation. The most effective way to control the thoughts is so to plan one's work as to insure the complete occupation of the mind with affairs that are wholly independent of sexual experiences or considerations. One should set a mark for himself so high above his present position that he is compelled to put forth strenuous and unremitting efforts in order to accomplish his aim. The old saying that, "Satan finds work for idle hands to do" is all too true. Anyone may observe the influence of idleness or even the influence of a partially occupied program upon the habits of the youth and young man. Beard and Rockwell, in their valuable work on this subject say: "Go to work; develop your muscles and brain; resolve to become at least useful if not famous. The activity which will be necessary in carrying out these ambitions will divert the mind from imaginary evils, if they are imaginary, and will be one of the best means to cure the real ones." CHAPTER VI. DEVELOPMENT. DEVELOPMENT. The development of the child within the uterus of the mother represents a chapter in the life history of every individual so important in its relations to maternity and paternity that every young man should be acquainted with at least its general features. As stated in the chapter on Reproduction, every living organism begins life as a single cell, or globule of protoplasm. In the case of the human subject, the cell from which each child begins its development is formed by the fusion of two cells or globules of protoplasm, one furnished by the mother, and called the ovum, or egg; the other furnished by the father, and called the spermatozoon. The egg is very much larger than the spermatozoon, and contains enough yolk material to afford nourishment for the embryo for a number of days.