In selecting eggs for setting, choose the freshest, those of moderate size, well-shaped, and having the air-vessel distinctly visible, either in the centre of the top of the egg, or slightly to the side, when the egg is held between the eye and a lighted candle, in a darkened room. Reject very small eggs, which generally have no yolk, those that are ill-shaped, and those of equal thickness at both ends, which latter is the usual shape of eggs with double yolks. These should be avoided, as they are apt generally to prove unfertile, or produce monstrosities. It has been stated that the sex of the embryo chicken can be ascertained by the position of the air-vessel; that if it be on the top the egg will produce a cockerel, and if on the side a pullet; but there is no proof of the truth of this, and, notwithstanding such assertions, it appears to be impossible to foretell the sex of the chick, from the shape of the egg or in any other way. In selecting eggs for the purpose of producing fowls that are to be kept for laying only, being non-sitters, choose eggs only from those hens that are prolific layers, for prolific laying is often as characteristic of some fowls of a breed as it is of the particular breeds, and by careful selection this faculty, like others, may be further developed, or continued if already fully developed. If carefully packed, eggs for setting may be carried great distances--hundreds and even thousands of miles--without injury; vibration and even moderate shaking, and very considerable changes of temperature, producing no ill effect upon the germ. The chief point is to prevent the escape of moisture by evaporation, and consequent admission of air. A hamper travels with less vibration than a box, and is therefore preferable, especially for a long journey. They should be packed in hay, by which they will be preserved from breakage much better than by being packed in short, close material like bran, chaff, oats, or sawdust; these being shaken into smaller space by the vibration of travelling, the eggs often strike and crack each other. The hamper or box should be large enough to admit of some soft, yielding packing material being placed all round the eggs. The bottom should be first covered with a good layer of hay, straw, or moss. It is a good plan to roll each egg separately in hay or moss, fastened with a little wool or worsted. They should be covered with well-rubbed straw, pressed down carefully and gently. The lid of the hamper should be sewed on tightly all round, or in three or four places at least. If a box is used, the lid should be fastened by cords or screws, but not with nails, as the hammering would probably destroy the germ of the egg.