=Chicken.=--The chicken scientifically is known as _Gallus domesticus_. For food purposes the chicken is eaten at various ages. The very young chicken is commonly called a broiler and is prepared for the table at varying ages from six to twelve weeks. Young chickens are also very commonly called spring chickens, since they occur in greater abundance in the spring than at any other time. Since the introduction of the modern method of incubation, however, the spring chicken may be had at all seasons of the year. The “broiler” and “spring chicken” may be regarded as synonymous terms, though the larger chicks are usually called spring chickens instead of broilers. _Full Grown Chickens._--The full grown chicken is better suited for food when still young. The flesh loses flavor and gains in toughness as the chicken grows older. There is no legal limit fixing the division of chickens into different classes with respect to age and the only criterion is the price and taste of the consumer. There is, perhaps, no objection to the use of old chickens for food purposes, provided they are not sold fraudulently as young chicks. The size and toughness of the pieces one often secures when ordering spring chicken is an indication that the age limit is not very definitely established. Both hens and roosters are used for food purposes, but especially the young roosters are devoted to food purposes while the young hens are often kept for the production of eggs. _Preparation of Chickens for Food Purposes._--In former times, when the chickens of commerce were derived chiefly from the farm, no special preparation was made before the chicken was marketed. The eggs were hatched in the old-fashioned way by the hens and the chicks sold to hucksters or in market, at various ages and without any special preparation or control. All this has been changed in later times by the introduction of scientific methods of breeding poultry. It has been demonstrated that the breeding and care of poultry require as much scientific and economic attention as is devoted to any other successful business. [Illustration: FIG. 12.--CHICKEN HOUSE, RHODE ISLAND EXPERIMENT STATION.] _The Incubator._--The introduction of the incubator for the hatching of eggs with the other necessary arrangements for the caring for young chicks has perhaps done more than any other one thing to revolutionize the method of preparing poultry for the market. By the use of the incubator the hatching of chicks is regulated with the utmost degree of nicety. A larger percentage of eggs produce chicks and the expense of the incubating process is greatly diminished. The incubator is in its widest significance a thermostat in which the eggs may be placed and maintained constantly at the temperature of the hen’s body, namely, about 102 degrees F. The arrangement of the chicken house and the other environments of the young chick are shown in Fig. 12.