=Care of sitting hens.= The best food for sitting hens is whole corn. As the hen will leave the nest only once a day, and not always daily unless removed, the food is given in a vessel from which she can eat it readily. The usual way is to keep a supply where the hens are, so that whenever they leave the nest they can get something to eat. Whether to let them choose their own time to leave the nest or to keep the nests closed except when they are let off at a regular time each day is a point to be determined in each case according to the circumstances. If all the hens in the same place are quiet and get along well together and do not quarrel for the possession of particular nests, they may be left very much to themselves; otherwise the poultry keeper should regulate things so that there will be no quarreling and no danger of a nest of eggs getting cold while two hens crowd on another nest and break some of the eggs in it. Besides grain the hens need water and a place to dust. Most sitting hens will dust themselves every time they leave the nest, if they have an opportunity to do so. As lice multiply rapidly on sitting hens, it is a good idea, even when the hen can dust herself, to apply an insect powder to her and to the nest two or three times during the period of incubation. The eggs may be tested at the end of the seventh day by using a light, as described on page 21. While fertility can be determined earlier, waiting until the seventh day enables one to tell more surely whether fertility is strong or weak, and to discard weak germs as well as infertile eggs. An infertile egg is clear, that is, shows no signs of development or decay, at every period of incubation. The eggs that rot are fertile eggs in which the germs have died. A rotten egg is distinguished from a fertile egg through the tester by the movement of the line between the transparent air space at the large end of the egg and the dark contents, this movement showing that the contents are in a fluid state. The eggs which are the most opaque and have the air space most distinctly marked are those which have the strongest germs. Eggs that are conspicuously light-colored (as they appear before the light) when compared with these may as well be discarded. If many eggs are discarded, those that remain may be given to a part of the hens, and the rest of the hens reset.