not it may be infected with pathogenic germs.

The conclusions of the in

vestigation are as follows (Bulletin No. 9, Hygienic Laboratory): "Seven samples of gelatine examined; one showed tetanus spores.

"Two samples showed an oval end-spore rod, whose identity was not proved, but, in stained specimens, it would be hard to distinguish from tetanus, if indeed not tetanus with diminished virulence.

"In tetanus investigations it is important to use freshly made bouillon, as the organism is apt not to germinate in bouillon over ten days old. The thermal death point of the organism isolated was found to be between twenty and thirty seconds at 100 degrees C.

"It is important, therefore, that gelatine to be used for injections should be boiled at least ten minutes on account of the variability of the thermal death point in different species of tetanus. Whether this amount of heating impairs in any way the hemostatic power of gelatine has not been settled, but in case it does it is believed that the danger from tetanus more than overbalances its therapeutic value.

"It is suggested that when, as in hospitals, there is likelihood of gelatine injections being used for hemostatic purposes the gelatine solution be sterilized by the fractional method on three successive days and kept ready for use in sterile containers."

From the data given above it is seen that gelatine may become infected and the material from which it is made for edible purposes should be healthful, sanitary and fit for food. It is not likely that tetanus germs would prove dangerous when taken into the stomach, but freedom from infection should be secured if possible. These investigations show the wisdom of the pure food law in forbidding the use of parts of animals unfit for food, whether manufactured or not, in the production of food products. It is evident that a sufficient quantity of fresh, sanitary material or material properly preserved can be obtained in this country or in other countries to supply the needs for edible gelatine without resorting to the use of inedible parts of hides, horns, hoofs and other waste and unfit portions of the animal. Summary. Above have been presented some of the principal meat foods, the analytical data which show their composition, the processes by means of which they are prepared and the principal methods, objectionable and otherwise, by which they are preserved.

Meat is a staple article of diet among almost all nations of men. The anatomical structure of the human animal indicates that his environment has adapted him to eating meats of all kinds. In other words, man is an omnivorous animal. He has been developed in an environment in which all kinds of meats and vegetables have ministered to his sustenance, and thus he is an omnivorous animal both by evolution and necessarily by heredity. That man can live and flourish without meat has been fully established by

experiments, but that man cannot be nourished by meat alone has likewise been fully established, so that if the human race were necessarily to be deprived either of animal or vegetable foods, it would be the animal food which must be sacrificed.

It is not the purpose of this manual to discuss the relative merits of vegetarianism as compared with the common diet of the human race. It may not be amiss, however, to say that probably in the United States especially, a larger quantity of meat is eaten than is either necessary or wholesome. The people of our country are better able to supply themselves with expensive foods than those of other countries, and of the common foods meats are far more expensive than cereals. The eating of larger quantities of cereals and smaller quantities of meat would probably be conducive both to economy and health. It appears to be certain that the meat eating of the future may not be regarded so much as a necessity as it has in the past, but that meats will be used more as condimental substances than as staple foods. In all meat, for instance, that costs 25 cents a pound, such as steaks, there is over one-third or a half of it which is inedible, so that the edible portion really costs double that amount. On the contrary, when a pound of flour or maize is purchased, the price of which is perhaps only one-eighth that of meat, the whole of it is edible. Thus, from the mere point of economy as well as of nutrition the superiority of cereals and other vegetable products is at once evident. On the one hand, a cereal is almost a complete food containing all the elements necessary to nutrition, and it costs only a few cents a pound. On the other hand, a steak or roast is only a partial food and it costs much more than cereals.

It is hoped that one purpose of this manual may be secured, namely, by showing the consumer the actual composition of the different kinds of food and their method of preparation he may be led in the selection of his food to follow the dictates of science and economy to a certain extent rather than merely the impulse of taste. The eating of such large quantities of meat is merely a habit which often is developed in children through the carelessness and ignorance of parents, much to the detriment of the child as well as to his future health and activity. It is believed that if the true principles of the use of meat were properly inculcated a large saving in the energy of the wage earner as well as those in more affluent circumstances would be secured.

Sound principles of economy establish a better condition of health and lead to greater activity and fruitful labor.

TERRESTRIAL ANIMAL OILS.

Terrestrial animal oils are obtained directly from parts of the animals which yield, at ordinary temperature, a substance which remains liquid. The fats which are in the feet of the animals are usually more liquid than in any other part of the body, and hence the natural animal oils are derived

largely from the feet. Among the most important are sheep's foot oil, horse foot oil, and neat's foot oil, which is obtained from the feet of cattle. These oils are all highly valued for technical purposes, especially for lubricating, and for this purpose bring a very high price. They are not used or should not be used for edible purposes, though they perhaps may sometimes be used in cooking. Neat's foot oil, especially, on account of its high price, is often subjected to adulteration, and is mixed for this purpose with cheap vegetable oils, such as cottonseed. Fish oil is also often used in the adulteration of neat's foot oil, though the addition of any of these oils to neat's foot oil raises the iodin number to a very high degree, and hence this addition is easily detected by the chemist.

Lard Oil.-Lard oil is one of the most important of terrestrial animal oils. It is made from lard by melting it and allowing it to slowly cool. The stearin in the product crystallizes first, and when it reaches a condition favoring the separation of the stearin the mass is subjected to straining or pressure, whereby the olein or liquid portion of the oil is separated, and thus, having been freed from the most of its stearin, remains liquid at ordinary temperature. The residue is known as lard stearin and is largely employed in the preparation of lard to give it a higher melting point and in the manufacture of oleomargarine.

Lard oil is used to some extent for edible purposes and is itself sometimes employed in the manufacture of oleomargarine when mixed with tallow or tallow stearin.

Properties of Lard Oil.—It is evident that the chemical and physical properties of lard oil are determined by the completeness with which the stearin is separated. Inasmuch, however, as the conditions of manufacture are nearly constant, lard oil has characteristics of a physical and chemical nature which do not vary greatly. The specific gravity of lard oil at 15 degrees. is about .916, and its iodin number varies from 68 to 75. When made of the best material it has a neutral taste, not an unpleasant odor, and, therefore, can be used for edible purposes without introducing any characteristic odor or flavor into the prepared food. In point of fact, however, it is not used to any extent for edible purposes except in the manufactured articles above mentioned. When carefully made and of the proper quality pure lard oil should be practically free from free acid.

Adulterations.-On account of the high value of lard oil for lubricating and other purposes it has been subjected to extensive adulterations. The addition of cheaper animal oils or vegetable oils has been largely practiced. Fish oil, blubber oil, and other marine animal oils have also been freely used in the adulteration of lard oil whenever the difference in price has rendered it advisable. These adulterations are of such a character that they can be detected only by the skilled microscopist and chemist. The other animal oils, both of marine and terrestrial origin, while important from a technical point of view, are of no significance in respect of edible qualities.

PART II.

POULTRY AND GAME BIRDS.

Application of Name.-The term poultry for descriptive purposes may be applied to those classes of feathered domesticated birds used for human food. It, therefore, includes practically all of the domesticated fowls. The term game bird, for the purpose of this manual, is applied to feathered animals which are wild and which are used for human food. This also may apply to almost all wild birds, since at times they practically all have been used for food purposes. Here only those in common use, both domesticated and wild, will be referred to. In connection with poultry the eggs of the birds will be considered.

DOMESTICATED FOWLS.

The principal domesticated fowls which are used for human food are chickens, turkeys, geese, ducks, and guinea hens. The most common of all is the chicken, the next perhaps are turkeys in this country and the goose in Europe. The others are more infrequently used but are highly prized.

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

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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

FIG. 12.-CHICKEN HOUSE, RHODE ISLAND EXPERIMENT STATION.

require as much scientific and economic attention as is devoted to any other successful business.

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.