[1] In the mammalia the word _foetus_ is often employed in the same
signification as embryo; it is especially applied to the embryo in
the later stages of uterine development.
[2] It may be proper to mention, as authors of this period who made
special researches on the development of the embryo--(1) Volcher
Coiter of Groningen, who, along with Aldrovandus of Bologna, made a
series of observations on the formation of the chick, day by day, in
the incubated egg, which were described in a work published in 1573,
and (2) Hieronymus Fabricius (ab Aquapendente), who, in his work _De
formato foetu_, first published at Padua in 1600, gave an interesting
account, illustrated by many fine engravings, of uterogestation and
the foetus of a number of quadrupeds and other animals, and in a
posthumous work entitled _De formatione ovi et pulli_, edited by J.
Prevost and published at Padua in 1621, described and illustrated by
engravings the daily changes of the egg in incubation. It is enough,
however, to say that Fabricius was entirely ignorant of the earlier
phenomena of development which occur in the first two or three days,
and even of the source of the embryonic rudiments, which he conceived
to spring, not from the yolk or true ovum, but from the chalazae or
twisted, deepest part of the white. The cicatricula he looked upon as
merely the vestige of the pedicle by which the yolk had previously
been attached to the ovary.
[3] Along with the work of W. Hunter must be mentioned a large
collection of unpublished observations by Dr James Douglas, which are
preserved in the Hunterian Museum of Glasgow University.
EMDEN, a maritime town of Germany, in the Prussian province of Hanover,
near the mouth of the Ems, 49 m. N.W. from Oldenburg by rail. Pop.
(1885) 14,019; (1905) 20,754. The Ems once flowed beneath its walls, but
is now 2 m. distant, and connected with the town by a broad and deep
canal, divided into the inner (or dock) harbour and the outer (or "free
port") harbour. The latter is 3/4 m. in length, has a breadth of nearly
400 ft., and since the construction of the Ems-Jade and Dortmund-Ems
canals, has been deepened to 38 ft., thus allowing the largest sea-going
vessels to approach its wharves. The town is intersected by canals
(crossed by numerous bridges), which bring it into communication with
most of the towns in East Friesland, of which it is the commercial
capital. The waterways which traverse and surround it and the character
of its numerous gabled medieval houses give it the appearance of an old
Dutch, rather than of a German, town. Of its churches the most
noteworthy are the Reformed "Great Church" (Grosse Kirche), a large
Gothic building completed in 1455, containing the tomb of Enno II. (d.
1540), count of East Friesland; the Gasthauskirche, formerly the church
of a Franciscan friary founded in 1317; and the Neue Kirche (1643-1647).
Of its secular buildings, the Rathaus (town-hall), built in 1574-1576,
on the model of that of Antwerp, with a lofty tower, and containing an
interesting collection of arms and armour, is particularly remarkable.
There are numerous educational institutions, including classical and
modern schools, and schools of commerce, navigation and telegraphy. The
town has two interesting museums. Emden is the seat of an active trade
in agricultural produce and live-stock, horses, timber, coal, tea and
wine. The deep-sea fishing industry of the town is important, the
fishing fleet in 1902 numbering 67 vessels. Machinery, cement, cordage,
wire ropes, tobacco, leather, &c. are manufactured. Emden is also of
importance as the station of the submarine cables connecting Germany
with England, North America and Spain. It has a regular steamboat
service with Borkum and Norderney.
Emden (Emuden, Emetha) is first mentioned in the 12th century, when it
was the capital of the Eemsgo (Emsgau, or county of the Ems), one of the
three hereditary countships into which East Friesland had been divided
by the emperor. In 1252 the countship was sold to the bishops of
Munster; but their rule soon became little more than nominal, and in
Emden itself the family of Abdena, the episcopal provosts and
castellans, established their practical independence. Towards the end of
the 14th century the town gained a considerable trade owing to the
permission given by the provost to the pirates known as
"Viktualienbruder" to make it their market, after they had been driven
out of Gothland by the Teutonic Order. In 1402, after the defeat of the
pirates off Heligoland by the fleet of Hamburg, Emden was besieged, but
it was not reduced by Hamburg, with the aid of Edzard Cirksena of
Greetsyl, until 1431. The town was held jointly by its captors till
1453, when Hamburg sold its rights to Ulrich Cirksena, created count of
East Friesland by the emperor Frederick III. in 1454. In 1544 the
Reformation was introduced, and in the following years numerous
Protestant refugees from the Low Countries found their way to the town.
In 1595 Emden became a free imperial city under the protection of
Holland, and was occupied by a Dutch garrison until 1744 when, with East
Friesland, it was transferred to Prussia. In 1810 Emden became the chief
town of the French department of Ems Oriental; in 1815 it was assigned
to Hanover, and in 1866 was annexed with that kingdom by Prussia.
See Furbringer, _Die Stadt Emden in Gegenwart und Vergangenheit_
(Emden, 1892).
EMERALD, a bright green variety of beryl, much valued as a gem-stone.
The word comes indirectly from the Gr. [Greek: _smaragdos_] (Arabic
_zumurrud_), but this seems to have been a name vaguely given to a
number of stones having little in common except a green colour. Pliny's
"smaragdus" undoubtedly included several distinct species. Much
confusion has arisen with respect to the "emerald" of the Scriptures.
The Hebrew word _nophek_, rendered emerald in the Authorized Version,
probably meant the carbuncle: it is indeed translated [Greek: _anthrax_]
in the Septuagint, and a marginal reading in the Revised Version gives
carbuncle. On the other hand, the word _bareqath_, rendered [Greek:
_smaragdos_] in the LXX., appears in the A.V. as carbuncle, with the
alternative reading of emerald in the R.V. It may have referred to the
true emerald, but Flinders Petrie suggests that it meant rock-crystal.
The properties of emerald are mostly the same as those described under
BERYL. The crystals often show simply the hexagonal prism and basal
plane. The prisms cleave, though imperfectly, at right angles to the
geometrical axis; and hexagonal slices were formerly worn in the East.
Compared with most gems, the emerald is rather soft, its hardness (7.5)
being but slightly above that of quartz. The specific gravity is low,
varying slightly in stones from different localities, but being for the
Muzo emerald about 2.67. The refractive and dispersive powers are not
high, so that the cut stones display little brilliancy or "fire." The
emerald is dichroic, giving in the dichroscope a bluish-green and a
yellowish-green image. The magnificent colour which gives extraordinary
value to this gem, is probably due to chromium. F. Wohler found 0.186%
of Cr2O3 in the emerald of Muzo,--a proportion which, though small, is
sufficient to impart an emerald-green colour to glass. The stone loses
colour when strongly heated, and M. Lewy suggested that the colour was
due to an organic pigment. Greville Williams showed that emeralds lost
about 9% of their weight on fusion, the specific gravity being reduced
to about 2.4.
The ancients appear to have obtained the emerald from Upper Egypt, where
it is said to have been worked as early as 1650 B.C. It is known that
Greek miners were at work in the time of Alexander the Great, and in
later times the mines yielded their gems to Cleopatra. Remains of
extensive workings were discovered in the northern Etbai by the French
traveller, F. Cailliaud, in 1817, and the mines were re-opened for a
short time under Mehemet Ali. "Cleopatra's Mines" are situated in Jebel
Sikait and Jebel Zabara near the Red Sea coast east of Assuan. They were
visited in 1891 by E.A. Floyer, and the Sikait workings were explored in
1900 by D.A. MacAlister and others. The Egyptian emeralds occur in
mica-schist and talc-schist.
On the Spanish conquest of South America vast quantities of emeralds
were taken from the Peruvians, but the exact locality which yielded the
stones was never discovered. The only South American emeralds now known
occur near Bogota, the capital of Colombia. The most famous mine is at
Muzo, but workings are known also at Coscuez and Somondoco. The emerald
occurs in nests of calcite in a black bituminous limestone containing
ammonites of Lower Cretaceous age. The mineral is associated with
quartz, dolomite, pyrites, and the rare mineral called "parisite"--a
fluo-carbonate of the cerium metals, occurring in brownish-yellow
hexagonal crystals, and named after J.J. Paris, who worked the emeralds.
It has been suggested that the Colombian emerald is not in its original
matrix. The fine stones are called _canutillos_ and the inferior ones
_morallion_.
In 1830 emeralds were accidentally discovered in the Ural Mountains. At
the present time they are worked on the river Takovaya, about 60 m. N.E.
of Ekaterinburg, where they occur in mica-schist, associated with
aquamarine, alexandrite, phenacite, &c. Emerald is found also in
mica-schist in the Habachthal, in the Salzburg Alps, and in granite at
Eidsvold in Norway. Emerald has been worked in a vein of pegmatite,
piercing slaty rocks, near Emmaville, in New South Wales. The crystals
occurred in association with topaz, fluorspar and cassiterite; but they
were mostly of rather pale colour. In the United States, emerald has
occasionally been found, and fine crystals have been obtained from the
workings for hiddenite at Stonypoint, Alexander county, N.C.
Many virtues were formerly ascribed to the emerald. When worn, it was
held to be a preservative against epilepsy, it cured dysentery, it
assisted women in childbirth, it drove away evil spirits, and preserved
the chastity of the wearer. Administered internally it was reputed to
have great medicinal value. In consequence of its refreshing green
colour it was naturally said to be good for the eyesight.
The stone known as "Oriental emerald" is a green corundum. Lithia
emerald is the mineral called hiddenite; Uralian emerald is a name given
to demantoid; Brazilian emerald is merely green tourmaline; evening
emerald is the peridot; pyro-emerald is fluorspar which phosphoresces
with a green glow when heated; and "mother of emerald" is generally a
green quartz or perhaps in some cases a green felspar.