Except when the flesh is poisoned by what they have eaten, the flesh of all birds is safe for food. Great differences, however, exist as to digestibility and wholesomeness, and these depend mainly upon three qualities: - 1. The amount and quality of fat. 2. The length and size of fibre. 3. The density or closeness of the fibre. Abundant, fresh air and exercise diminish fat and improve its quality, and render the fibre of the flesh shorter and closer; whereas want of air and exercise increase the quantity and deteriorate the quality of the fat, and produce a loose, long-fibred flesh.

The fat of all birds is difficult of digestion by weak stomachs, and becomes more apt to disagree in proportion as it is more oily in quality, and when over-heated readily produces those irritating compounds (acrolein and fatty acids) already spoken of under the head of meats; and as the depth of the lean is not great, a large proportion of it becomes saturated with the overheated surface-fat and participates in its unwholesomeness. This disadvantage of course increases with the smallness of the bird in proportion to its fat. The consequence of this combination of circumstances is that tamed and fattened birds or "poultry" are less nutritious, less easily digested, and more apt to disagree than wild unfattened birds or "game;" this is illustrated in the case of pheasants, which are rendered much less wholesome in the present day, when they are coddled and fed like tame poultry, than they used to be when they were left in a wild and natural condition, and in the case of barndoor fowls, which are more wholesome than those carefully fattened in yards and cages. In large poultry, such as turkey, the deeper lean is almost out of reach of the poisonous influence of the outside over-heated skin and fat, and would be very wholesome, were it not for the bad effects of inordinate over-feeding, with want of exercise, which impregnates all the tissues with oil. Water-birds even when wild become more deeply impregnated with fat than land birds, and are proportionately more apt to disagree.

Venison and Hare rank with game, and the same observations apply to them as to game birds.