EGG. 680 EGG. lower alga> and fungi, the two sex-cells (gametes) do not ditler in appearance, a condition which is called 'isogamy.' Most phmts, however, are not isogamous, but their pairing gametes are verv dissimilar. The male gamete, called the sperm, is small and usually motile hy means of cilia : while the female gamete, called the egg. EGG :
- 6, of club-mosB ; 6, of fern ; c. of liverwort.
is relatively large and passive. Plants with such dissimilar gametes are said to be 'heter- ogamous.' Both sperms and eggs are single, naked cells, hut the former are characterized by their activity, the latter by their food-supply. As in all living cells, the egg consists of a nucleus invested by more or less cytoplasm, in this case the cytoplasm being conspicuous in amount and containing an abundance of reserved food. Usiuill.v a special organ is set apart to develop within itself a single egg. Among algie and fungi this female organ is generally a single spherical cell, and is called the 'oogonium' : among the bryophytes (mosses and their allies), pteri- dophytes (ferns and their allies), and gymno- sperms (conifers and their allies), the female organ is a many-celled, tlask-shaped structure called the 'archegonium,' in whose venter (the bulbous part) the egg is organized; while among spermatophytes (seed-plants) there is no female organ, the egg appearing as a free cell in the embryo-sac which is imbedded in the ovule. In most cases a solitary egg is formed by a se.x- organ, in which it passively remains till fertil- ized by the spore, but there are some interest- ing exceptions. For example, in the conunon rockweed (Fucus), a brown alga of the .sea- shore, some of the species have oijgonia which produce eight eggs, that are discharged into the water for fertilization. Under ordinary circumstances, an egg must unite with a sperm, tliat is, it must be fertilized before it can accom- plish anything. The new cell thus formed by the fusinn of two cells is known as the 'oiispore' or 'fertilized egg.' Occasionally, however, an un- fertilized egg may produce a new plant, the phenomenon Iieing known as 'parthenogenesis.' Parthenogenesis is rather common among the lower plants, and it is not entirely unknown even among seed-plants, although its occurrence there has been reported in very few forms. See Em- i<KYo : Cell : Cytology : Sperm ; P.ethenogene- SIS ; FEinlLIZ.TION. EGG. As a food, i)erhaps no article of ani- mal origin is more common in all countries or served in a greater variety of ways. Hens' eggs are most popular, although the eggs of ducks, geese, and guinea-fowls are used to some extent. More rarely turkeys' eggs are eaten, but they are generally of greater value for hatching. The eggs of the lapwing (q.v.). called ■plover-eggs,' are prized in England and tiermany, while the eggs of sea-birds have long been gathered for food. Other eggs besides those of birds are sometimes eaten. Turtle-eggs are higlily prized in most countries where they are abundant. The eggs of the terrapin are usually served with the llcsh in some of the ways of preparing it for the table. Fish-eggs, especially those of the stur- geon, under the name of caviar (q.v.). are eaten in large (piantities. preserved with salt. Shad- roe is also a familiar example of the use of tish eggs as food. Mention may also be made of the use by some races of the eggs of alligators, lizards, serpents, and various insects. Cooking of Eggs. The methods of serving eggs alone, or in combination with other food mate- rials, are very numerous. Cocfl'Ced in various ways they are a favorite animal food, taking the place of meat to a certain extent, while raw eggs, usually seasoned in some way, are by no means infrequently eaten. Boiled eggs are often used for garnishing or ornamenting different foods. Eggs are combined with other materials in various ways in many made dishes. They are used in making cakes and such foods to improve the llavor. color, and texture, while in ciistards, creams, etc., they thicken the material and give it the desired consistency. The while of the egg is employed in making icings and confection- ery. Well-beaten egg-white incloses air in small bubbles, which in mixing become distributed throughout the mass of dough of cakes and similar foods. The heat of cooking expands the bubbles, which become firm; the porous structure is retained, thus improving both the texture and flavor of the prodict. The power of eggs to inclose and retain air. when beaten, varies, being greatest in the fresh egg and mueli less in packed (jr old eggs. There are several simple ways of cooking eggs which are very conunonly followed. 'J bus, the egg in the shell is cooked by immer- sion in hot or boiling water, or is less commonly roasted: or after removal from the shell, the egg is cooked in hot Avater or in hot fat. In the latter case it may or may not be beaten or stirred. Combined with other materials to form variously made dishes, eggs are boiled, baked, steamed, or fried, as the case may be. The total number of methods of serving and prepar- ing eggs is very large, but in nearly every case it will be found that the method of prei)aration is only a more or less elaborate modification of one of the simple methods of cooking. When cooked in dilTerent ways there are marked changes in the appearance and structure of eggs. If the egg-white is gently warmed no change is noticed until the temperature reaches 134° F., when (fiagulation begins. White fibres appear, which become more numerous, until at about lliO° F. the whole mass is coagulated, the white almost opaque, yet tender and jelly like. If the temperature is raised and continued to 212° F. (the temperature of boiling water), the coagu-
