masses attain may be gathered from the fact that the spawn of the angler-fish, Lophius piscatorius, takes the form of a sheet from 2 to 3 ft. wide, and 30 ft. long. Another remarkable feature of these floating eggs is their transparency, inasmuch as they are extremely difficult to see, and hence they probably escape the rapacious maws of spawn-eating animals. The cod tribe and flat-fishes lay floating eggs of this description.
The maximum number of eggs laid by fishes varies greatly, some species laying relatively few, others an enormous number. But in all cases the number increases with the weight and age of the fish. Thus it has been calculated that the number laid by the salmon is roughly about 1000 to every pound weight of the fish, a 15 ℔ salmon laying 15,000 eggs. The sturgeon lays about 7,000,000; the herring 50,000; the turbot 14,311,000; the sole 134,000; the perch 280,000. Briefly, the number is greatest where the risks of destruction are greatest.
The eggs of the degenerate fishes known as the lampreys and hag-fishes are remarkable for the fact that in the latter they are large in size, cylindrical in shape, and provided at each end with hooklets whereby they adhere one to another; while in the lampreys they are extremely small and embedded in a jelly.
Molluscs.—Among the Mollusca, Crustacea and Insecta yolk-stored eggs of very remarkable forms are commonly produced.
In variety, in this connexion, the Mollusca must perhaps be given the first place. This diversity, indeed, is strikingly illustrated by the eggs of the Cephalopoda. In the squids (Loligo), for example, the eggs are enclosed in long cylindrical cases, of which there are several hundreds, attached by one end to a common centre; the whole series looking strangely like a rough mop-head. Each case, in such a cluster, contains about 250 eggs, or about 40,000 in all. By way of contrast the eggs of the true cuttle-fish (Sepia) are deposited separately, each enclosed in a tough, black, pear-shaped capsule which is fastened by a stalk to fronds of sea-weed or other object. They appear to be extruded at short intervals, till the full complement is laid, the whole forming a cluster looking like a bunch of grapes. The octopus differs yet again in this matter, its eggs being very small, berry-like, and attached to a stalk which runs through the centre of the mass.
The eggs of the univalve Mollusca are hardly less varied in the shapes they take. In the common British Purpura lapillus they resemble delicate pink grains of rice set on stalks; in Busycon they are disk-shaped, and attached to a band nearly 3 ft. long. The eggs of the shell-bearing slugs (Testacella) are large, and have the outer coat so elastic that if dropped on a stone floor they will rebound several inches; while some of the snails (Bulimus) lay eggs having a white calcareous and slightly iridescent shell, in size and shape closely resembling the egg of the pigeon. Some are even larger than the egg of the wood-pigeon. The beautiful violet-snail (Ianthina)—a marine species—carries its eggs on the under side of a gelatinous raft. No less remarkable are the eggs of the whelk; since, like those of the squids, they are not laid separately but enveloped in capsules, and these to the number of many hundreds form the large, ball-like masses so commonly met with on the seashore. When the eggs in these capsules hatch, the crowd of embryos proceed to establish an internecine warfare, devouring one another till only the strongest survives!
With the Mollusca, as with other groups of animals, where the eggs are exposed to great risks they are small, produced in great numbers, and give rise to larvae. This is well illustrated by the common oyster which annually disperses about 60,000,000 eggs. But where the risk of destruction is slight, the eggs are large and produce young differing from the parent only in size, as in the case of the pigeon-like eggs of Bulimus.
Crustaceans.—Among the higher Crustacea, as a rule, the eggs are carried by the female, attached to special appendages on the under side of the body. But in some—Squillas—they are deposited in burrows. Generally they are relatively small so that the young which emerge therefrom differ markedly in appearance from the parents, but in deep-sea and freshwater species the eggs are large, when the young, on emerging, differ but little from the adults in appearance.
Insects, &c.—The eggs of insects though minute, are also remarkable for the great variety of form which they present, while they are frequently objects of great beauty owing to the sculptured markings of the shell. They are generally laid in clusters, either on the ground, on the leaves of plants, or in the water. Some of the gnats (Culex) lay them on the water. Cylindrical in shape they are packed closely together, set on end, the whole mass forming a kind of floating raft. Frequently, as in the case of the stick and leaf insect, the eggs are enclosed in capsules of very elaborate shapes and highly ornamented.
As to the rest of the Invertebrata—above the Protozoa the eggs are laid in water, or in damp places. In the former case they are as a rule small, and give rise to larvae; while eggs hatched on land are sometimes enclosed in capsules, “cocoons,” as in the case of the earthworm, where this capsule is filled with a milky white fluid, of a highly nutritious character, on which the embryos feed.
Among some invertebrates two different kinds of eggs are laid by the same individual. The water-flea, Daphnia (a crustacean), lays two kinds of eggs known as “summer” and “winter” eggs. The summer eggs are carried by the female in a “brood-pouch” on the back. The “winter” eggs, produced at the approach of winter, differ markedly in appearance from the summer eggs, being larger, darker in colour, thicker shelled, and enclosed in a capsule formed from the shell or carapace, of the parent’s body. “Winter eggs,” however, may be produced in the height of summer. While the “summer eggs” are unfertilized, the winter eggs are fertilized by the male, and possess the remarkable power of lying dormant for months or even years before they develop. The production of these two kinds of eggs is a device to overcome the cold of winter, or the drying up of the pools in which the species lives, during the heat of the summer. The power of resistance which such eggs possess may be seen in the fact that a sample of mud which had been kept dry for ten years still contained living eggs. In deep water where neither drought nor winter cold can seriously affect the Daphnias, they propagate all the year round by unfertilized “summer” eggs.
Bibliography.—For further details on this subject the following authors should be consulted:—Mammals: F. E. Beddard, “Remarks on the Ovary of Echidna,” Proc. Roy. Phys. Soc. Edin. vol. viii. (1885); W. H. Caldwell, “The Embryology of Monotremata and Marsupialia,” Phil. Trans. Roy. Soc. vol. 178 (1887); E. B. Poulton, “The Structures connected with the Ovarian Ovum of the Marsupialia and Monotremata,” Quart. Journ. Micros. Sci. vol. xxiv. (1884). Birds, Systematic:—H. Seebohm, Coloured Figures of the Eggs of British Birds (1896); A. Newton, Ootheca Wooleyana (1907); E. Oates, Cat. Birds’ Eggs Brit. Mus. (appearing), vols. i.-iv. published. General:—A. Newton, Dictionary of Birds (1896). Colouring matter:—Newbegin, Colour in Nature (1898). Reptiles and Amphibia:—H. Gadow, “Reptiles,” Camb. Nat. Hist. (1901); G. A. Boulenger, “The Tailless Batrachians of Europe,” Ray Soc. (1896). Fishes:—Bridge and Boulenger, “Fishes, Ascidians, &c.,” Camb. Nat. Hist. (1904); B. Dean, Fishes Living and Fossil (1895); J. T. Cunningham, Marketable Marine Fishes (1896). Invertebrate:—G. H. Carpenter, Insects. Their Structure and Life (1899); L. C. Miall, A History of Aquatic Insects (1895); T. R. R. Stebbing, Crustacea, Internat. Sci. series (1893); M. C. Cooke, “Mollusca,” Camb. Nat. Hist. (1906). For further references to the above and other Invertebrate groups see various text-books on Entomology, Zoology. (W. P. P.)
EGGENBERG, HANS ULRICH VON, Prince (1568–1634),
Austrian statesman, was a son of Siegfried von Eggenberg (d.
1594), and began life as a soldier in the Spanish service, becoming
about 1596 a trusted servant of the archduke of Styria, afterwards
the emperor Ferdinand II. Having become a Roman
Catholic, he was soon the chancellor and chief adviser of
Ferdinand, whose election as emperor he helped to secure in 1619.
He directed the imperial policy during the earlier part of the
Thirty Years’ War, and was in general a friend and supporter of
Wallenstein, and an opponent of Maximilian I., duke of Bavaria,
and of Spain. He was largely responsible for Wallenstein’s
return to the imperial service early in 1632, and retired from
public life just after the general’s murder in February 1634, dying
