EGO

(Germ, ei.) The ovum of birds and oviparous animals. The changes which ihe hen's egg undergoes during incubation have been described by Sir E. Home in the Phi to top hic a i Transactions for the year 1822 (page 339), and illustrated by a beautiful series of plates after Bauer's drawings: the same volume also contains a valuable paper by l)r. rrout on the same subject, but chiefly in reference to the chemical changes of the egg during that proce . The specific gravity of new-laid eggs at first rather exceeds that of water, varying from 11)80 to 1090; but they soon becomo lighter, and swim on water, in consequence of evaporation through the pores of the shell. When an egg is boiled in water, and suffered to cool in the air, it loses about 32 hundredths of a grain of saline matter, together with a trace of animal matter and free alkali. The mean weight of a hen's egg is about 875 grains, of which tho shell and its inner membrane weigh i-37 grains, the albumen or white 529-8 grs., and the yolk 2518 grs. The shell contains about 2 per cent, of animal matter and 1 per cent, of tho phosphates of lime and magnesia, the remainder being carbonate of lime, with a trace of carbonate of niagnesis. When the yolk of a hard-boiled egg is digested in repeated portions of strong alcohol, there remains a white residue having the leading characters of albumen, but containing phosphorus in some peculiar state of combination; the alcoholic solution is yellow, and deposits a crystalline fatty matter, and when distilled leaves a yellow oil. The albumen of the egg contains sulphur. The use of the phosphorus is to yield phosphoric acid to form the bones of the chick; but the source of the lime with which it is combined is not apparent, for it has not been detected in the soft parts of the egg, and hitherto no vascular com muni cation has been discovered between the chick and the shell. The trade in eggs is of great value and importance; the number of eggs imported into England from various parts of the Continent, for the year ending Jan. 5, 1S39. was 83.745,723; and the gro amount of duty received for the same was 29,1 1W. [s. 401]