[Illustration: FIG. 42.--Transverse section of a bud, in which the
leaves are arranged in an accumbent manner.
FIG. 43.--Transverse section of a bud, in which the leaves are
arranged in an equitant manner.
FIG. 44.--Transverse section of a bud, showing two leaves folded in
an obvolute manner. Each is conduplicate, and one embraces the edge
of the other.
FIG. 45.--Transverse section of a bud, showing two leaves arranged
in a supervolute manner.]
The arrangement of the leaves in the bud is termed _vernation_ or
_prefoliation_. In considering vernation we must take into account
both the manner in which each individual leaf is folded and also the
arrangement of the leaves in relation to each other. These vary in
different plants, but in each species they follow a regular law. The
leaves in the bud are either placed simply in apposition, as in the
mistletoe, or they are folded or rolled up longitudinally or
laterally, giving rise to different kinds of vernation, as delineated
in figs. 36 to 45, where the folded or curved lines represent the
leaves, the thickened part being the midrib. The leaf taken
individually is either folded longitudinally from apex to base, as in
the tulip-tree, and called _reclinate_ or _replicate_; or rolled up in
a circular manner from apex to base, as in ferns (fig. 36), and called
_circinate_; or folded laterally, _conduplicate_ (fig. 37), as in oak;
or it has several folds like a fan, _plicate_ or _plaited_ (fig. 38),
as in vine and sycamore, and in leaves with radiating vernation, where
the ribs mark the foldings; or it is rolled upon itself, _convolute_
(fig. 39), as in banana and apricot; or its edges are rolled inwards,
_involute_ (fig. 40), as in violet; or outwards, _revolute_ (fig. 41),
as in rosemary. The different divisions of a cut leaf may be folded or
rolled up separately, as in ferns, while the entire leaf may have
either the same or a different kind of vernation. The leaves have a
definite relation to each other in the bud, being either opposite,
alternate or verticillate; and thus different kinds of vernation are
produced. Sometimes they are nearly in a circle at the same level,
remaining flat or only slightly convex externally, and placed so as to
touch each other by their edges, thus giving rise to _valvate_
vernation. At other times they are at different levels, and are
applied over each other, so as to be _imbricated_, as in lilac, and in
the outer scales of sycamore; and occasionally the margin of one leaf
overlaps that of another, while it in its turn is overlapped by a
third, so as to be _twisted_, _spiral_ or _contortive_. When leaves
are applied to each other face to face, without being folded or rolled
together, they are _appressed_. When the leaves are more completely
folded they either touch at their extremities and are _accumbent_ or
_opposite_ (fig. 42), or are folded inwards by their margin and become
_induplicate_; or a conduplicate leaf covers another similarly folded,
which in turn covers a third, and thus the vernation is _equitant_
(fig. 43), as in privet; or conduplicate leaves are placed so that the
half of the one covers the half of another, and thus they become
_half-equitant_ or _obvolute_ (fig. 44), as in sage. When in the case
of convolute leaves one leaf is rolled up within the other, it is
_supervolute_ (fig. 45). The scales of a bud sometimes exhibit one
kind of vernation and the leaves another. The same modes of
arrangement occur in the flower-buds.
Leaves, after performing their functions for a certain time, wither
and die. In doing so they frequently change colour, and hence arise
the beautiful and varied tints of the autumnal foliage. This change
of colour is chiefly occasioned by the diminished circulation in the
leaves, and the higher degree of oxidation to which their chlorophyll
has been submitted.
Leaves which are articulated with the stem, as in the walnut and
horse-chestnut, fall and leave a scar, while those which are
continuous with it remain attached for some time after they have lost
their vitality. Most of the trees of Great Britain have deciduous
leaves, their duration not extending over more than a few months,
while in trees of warm climates the leaves often remain for two or
more years. In tropical countries, however, many trees lose their
leaves in the dry season. The period of defoliation varies in
different countries according to the nature of their climate. Trees
which are called evergreen, as pines and evergreen-oak, are always
deprived of a certain number of leaves at intervals, sufficient being
left, however, to preserve their green appearance. The cause of the
fall of the leaf in cold climates seems to be deficiency of light and
heat in winter, which causes a cessation in the functions of the cells
of the leaf. The fall is directly caused by the formation of a layer
of tissue across the base of the leaf-stalk; the cells of this layer
separate from one another and the leaf remains attached only by the
fibres of the veins until it becomes finally detached by the wind or
frost. Before its fall the leaf has become dry owing to loss of water
and the removal of the protoplasm and food substances to the stem for
use next season; the red and yellow colouring matters are products of
decomposition of the chlorophyll. Inorganic and other waste matters
are stored in the leaf-tissue and thus got rid of by the plant. The
leaf scar is protected by a corky change (suberization) in the walls
of the exposed cells. (A. B. R.)
LEAF-INSECT, the name given to orthopterous insects of the family
Phasmidae, referred to the single genus _Phyllium_ and characterized by
the presence of lateral laminae upon the legs and abdomen, which, in
association with an abundance of green colouring-matter, impart a broad
and leaf-like appearance to the whole insect. In the female this
deceptive resemblance is enhanced by the large size and foliaceous form
of the front wings which, when at rest edge to edge on the abdomen,
forcibly suggest in their neuration the midrib and costae of an ordinary
leaf. In this sex the posterior wings are reduced and functionless so
far as flight is concerned; in the male they are ample, membranous and
functional, while the anterior wings are small and not leaf-like. The
freshly hatched young are reddish in colour; but turn green after
feeding for a short time upon leaves. Before death a specimen has been
observed to pass through the various hues of a decaying leaf, and the
spectrum of the green colouring matter does not differ from that of the
chlorophyll of living leaves. Since leaf-insects are purely vegetable
feeders and not predaceous like mantids, it is probable that their
resemblance to leaves is solely for purposes of concealment from
enemies. Their egg capsules are similarly protected by their likeness to
various seeds. Leaf-insects range from India to the Seychelles on the
one side, and to the Fiji Islands on the other. (R. I. P.)
LEAGUE. 1. (Through Fr. _ligue_, Ital. _liga_, from Lat. _ligare_, to
bind), an agreement entered into by two or more parties for mutual
protection or joint attack, or for the furtherance of some common
object, also the body thus joined or "leagued" together. The name has
been given to numerous confederations, such as the Achaean League
(q.v.), the confederation of the ancient cities of Achaia, and
especially to the various holy leagues (_ligues saintes_), of which the
better known are those formed by Pope Julius II. against Venice in 1508,
often known as the League of Cambrai, and against France in 1511. "The
League," in French history, is that of the Catholics headed by the
Guises to preserve the Catholic religion against the Huguenots and
prevent the accession of Henry of Navarre to the throne (see FRANCE:
_History_). "The Solemn League and Covenant" was the agreement for the
establishment of Presbyterianism in both countries entered into by
England and Scotland in 1643 (see COVENANTERS). Of commercial leagues
the most famous is that of the Hanse towns, known as the Hanseatic
League (q.v.). The word has been adopted by political associations, such
as the Anti-Corn Law League, the Irish Land League, the Primrose League
and the United Irish League, and by numerous social organizations.
"League" has also been applied to a special form of competition in
athletics, especially in Association football. In this system clubs
"league" together in a competition, each playing every other member of
the association twice, and the order of merit is decided by the points
gained during the season, a win counting two and a draw one.
2. (From the late Lat. _leuga_, or _leuca_, said to be a Gallic word;
the mod. Fr. _lieue_ comes from the O. Fr. _liue_; the Gaelic _leac_,
meaning a flat stone posted as a mark of distance on a road, has been
suggested as the origin), a measure of distance, probably never in
regular use in England, and now only in poetical or rhetorical language.
It was the Celtic as opposed to the Teutonic unit, and was used in
France, Spain, Portugal and Italy. In all the countries it varies with
different localities, and the ancient distance has never been fixed. The
kilometric league of France is fixed at four kilometres. The nautical
league is equal to three nautical miles.
LEAKE, WILLIAM MARTIN (1777-1860), British antiquarian and topographer,
was born in London on the 14th of January 1777. After completing his
education at the Royal Military Academy, Woolwich, and spending four
years in the West Indies as lieutenant of marine artillery, he was sent
by the government to Constantinople to instruct the Turks in this branch
of the service. A journey through Asia Minor in 1800 to join the British
fleet at Cyprus inspired him with an interest in antiquarian topography.
In 1801, after travelling across the desert with the Turkish army to
Egypt, he was, on the expulsion of the French, employed in surveying the
valley of the Nile as far as the cataracts; but having sailed with the
ship engaged to convey the Elgin marbles from Athens to England, he lost
all his maps and observations when the vessel foundered off Cerigo.
Shortly after his arrival in England he was sent out to survey the coast
of Albania and the Morea, with the view of assisting the Turks against
attacks of the French from Italy, and of this he took advantage to form
a valuable collection of coins and inscriptions and to explore ancient
sites. In 1807, war having broken out between Turkey and England, he was
made prisoner at Salonica; but, obtaining his release the same year, he
was sent on a diplomatic mission to Ali Pasha of Iannina, whose
confidence he completely won, and with whom he remained for more than a
year as British representative. In 1810 he was granted a yearly sum of
£600 for his services in Turkey. In 1815 he retired from the army, in
which he held the rank of colonel, devoting the remainder of his life to
topographical and antiquarian studies, the results of which were given
to the world in the following volumes: _Topography of Athens_ (1821);
_Journal of a Tour in Asia Minor_ (1824); _Travels in the Morea_ (1830),
and a supplement, _Peloponnesiaca_ (1846); _Travels in Northern Greece_
(1835); and _Numismata Hellenica_ (1854), followed by a supplement in
1859. A characteristic of the researches of Leake was their
comprehensive minuteness, which was greatly aided by his mastery of
technical details. His _Topography of Athens_, the first attempt at a
scientific treatment of the subject, is still authoritative in regard to
many important points (see ATHENS). He died at Brighton on the 6th of
January 1860. The marbles collected by him in Greece were presented to
the British Museum; his bronzes, vases, gems and coins were purchased by
the university of Cambridge after his death, and are now in the
Fitzwilliam Museum. He was elected F.R.S. and F.R.G.S., received the
honorary D.C.L. at Oxford (1816), and was a member of the Berlin Academy
of Sciences and correspondent of the Institute of France.
See _Memoir_ by J. H. Marsden (1864); the _Architect_ for the 7th of
October 1876; E. Curtius in the _Preussische Jahrbücher_ (Sept.,
1876); J. E. Sandys, _Hist. of Classical Scholarship_, iii. (1908), p.
442.
LEAMINGTON, a municipal borough and health resort of Warwickshire,
England, on the river Leam near its junction with the Avon, 98 m. N.W.
from London, served by the Great Western and London & North Western
railways. Pop. (1901) 26,888. The parliamentary boroughs of Leamington
and Warwick were joined into one constituency in 1885, returning one
member. The centres of the towns are 2 m. apart, Warwick lying to the
west, but they are united by the intermediate parish of New Milverton.
There are three saline springs, and the principal pump-rooms, baths and
pleasant gardens lie on the right bank of the river. The chief public
buildings are the town hall (1884), containing a free library and
school of art; and the Theatre Royal and assembly room. The parish
church of All Saints is modernized, and the other churches are entirely
modern. The S. Warwickshire hospital and Midland Counties Home for
incurables are here. Leamington High School is an important school for
girls. There is a municipal technical school. Industries include iron
foundries and brickworks. The town lies in a well-wooded and picturesque
country, within a few miles of such interesting towns as Warwick,
Kenilworth, Coventry and Stratford-on-Avon. It is a favourite hunting
centre, and, as a health resort, attracts not only visitors but
residents. The town is governed by a mayor, 8 aldermen, and 24
councillors. Area, 2817 acres.
Leamington was a village of no importance until about 1786, when baths
were first erected, though the springs were noticed by Camden, writing
about 1586. The population in 1811 was only 543, The town was
incorporated in 1875. The name in former use was Leamington Priors, in
distinction from Leamington Hastings, a village on the upper Leam. By
royal licence granted in 1838 it was called Royal Leamington Spa.
LÉANDRE, CHARLES LUCIEN (1862- ), French caricaturist and painter, was
born at Champsecret (Orne), and studied painting under Bin and Cabanel.
From 1887 he figured among the exhibitors of the Salon, where he showed
numerous portraits and genre pictures, but his popular fame is due to
his comic drawings and caricatures. The series of the "Gotha des
souverains," published in _Le Rire_, placed him in the front rank of
modern caricaturists. Besides his contributions to _Le Rire_, _Le
Figaro_ and other comic journals, he published a series of albums:
_Nocturnes_, _Le Musée des souverains_, and _Paris et la province_.
Léandre produced admirable work in lithography, and designed many
memorable posters, such as the "Yvette Guilbert." "Les nouveaux mariés,"
"Joseph Prudhomme," "Les Lutteurs," and "La Femme au chien." He was
created a knight of the Legion of Honour.
LEAP-YEAR (more properly known as _bissextile_), the name given to the
year containing 366 days. The astronomers of Julius Caesar, 46 B.C.,
settled the solar year at 365 days 6 hours. These hours were set aside
and at the end of four years made a day which was added to the fourth
year. The English name for the bissextile year is an allusion to the
result of the interposition of the extra day; for after the 29th of
February a date "leaps over" the day of the week on which it would fall
in ordinary years. Thus a birthday on the 10th of June, a Monday, will
in the next year, if a leap-year, be on the 10th of June, a Wednesday.
Of the origin of the custom for women to woo, not be wooed, during
leap-year no satisfactory explanation has ever been offered. In 1288 a
law was enacted in Scotland that "it is statut and ordaint that during
the rein of hir maist blissit Megeste, for ilk yeare knowne as lepe
yeare, ilk mayden ladye of bothe highe and lowe estait shall hae liberte
to bespeke ye man she likes, albeit he refuses to taik hir to be his
lawful wyfe, he shall be mulcted in ye sum ane pundis or less, as his
estait may be; except and awis gif he can make it appeare that he is
betrothit ane ither woman he then shall be free." A few years later a
like law was passed in France, and in the 15th century the custom was
legalized in Genoa and Florence.
LEAR, EDWARD (1812-1888), English artist and humorist, was born in
London on the 12th of May 1812. His earliest drawings were
ornithological. When he was twenty years old he published a brilliantly
coloured selection of the rarer Psittacidae. Its power attracted the
attention of the 13th earl of Derby, who employed Lear to draw his
Knowsley menagerie. He became a permanent favourite with the Stanley
family; and Edward, 15th earl, was the child for whose amusement the
first _Book of Nonsense_ was composed. From birds Lear turned to
landscape, his earlier efforts in which recall the manner of J. D.
Harding; but he quickly acquired a more individual style. About 1837 he
set up a studio at Rome, where he lived for ten years, with summer tours
in Italy and Sicily, and occasional visits to England. During this
period he began to publish his _Illustrated Journals of a Landscape
Painter_: charmingly written reminiscences of wandering, which
ultimately embraced Calabria, the Abruzzi, Albania, Corsica, &c. From
1848-1849 he explored Greece, Constantinople, the Ionian Islands, Lower
Egypt, the wildest recesses of Albania, and the desert of Sinai. He
returned to London, but the climate did not suit him. In 1854-1855 he
wintered on the Nile, and migrated successively to Corfu, Malta and
Rome, finally building himself a villa at San Remo. From Corfu Lear
visited Mount Athos, Syria, Palestine, and Petra; and when over sixty,
by the assistance of Lord Northbrock, then Govenor-General, he saw the
cities and scenery of greatest interest within a large area of India.
From first to last he was, in whatever circumstances of difficulty or
ill-health, an indomitable traveller. Before visiting new lands he
studied their geography and literature, and then went straight for the
mark; and wherever he went he drew most indefatigably and most
accurately. His sketches are not only the basis of more finished works,
but an exhaustive record in themselves. Some defect of technique or
eyesight occasionally left his larger oil painting, though nobly
conceived, crude or deficient in harmony; but his smaller pictures and
more elaborate sketches abound in beauty, delicacy, and truth. Lear
modestly called himself a topographical artist; but he included in the
term the perfect rendering of all characteristic graces of form, colour,
and atmosphere. The last task he set himself was to prepare for popular
circulation a set of some 200 drawings, illustrating from his travels
the scenic touches of Tennyson's poetry; but he did not live to complete
the scheme, dying at San Remo on the 30th of January 1888. Until sobered
by age, his conversation was brimful of humorous fun. The paradoxical
originality and ostentatiously uneducated draughtsmanship of his
numerous nonsense books won him a more universal fame than his serious
work. He had a true artist's sympathy with art under all forms, and
might have become a skilled musician had he not been a painter.
Swainson, the naturalist, praised young Lear's great red and yellow
macaw as "equalling any figure ever painted by Audubon in grace of
design, perspective, and anatomical accuracy." Murchison, examining his
sketches, complimented them as rigorously embodying geological truth.
Tennyson's lines "To E.L. on his Travels in Greece," mark the poet's
genuine admiration of a cognate spirit in classical art. Ruskin placed
the _Book of Nonsense_ first in the list of a hundred delectable volumes
of contemporary literature, a judgment endorsed by English-speaking
children all over the world.
See _Letters of Edward Lear to Chichester Fortescue, Lord Carlingford,
and Frances, Countess Waldegrave_ (1907), edited by Lady Strachey,
with an introduction by Henry Strachey. (F. L.*)
LEASE (derived through the Fr. from the Lat. _laxare_, to loosen), a
certain form of tenure, or the contract embodying it, of land, houses,
&c.; see LANDLORD AND TENANT.
LEATHER (a word which appears in all Teutonic languages; cf. Ger.
_Leder_, Dutch _leer_ or _leder_, Swed. _läder_, and in such Celtic
forms as Welsh _llader_), an imputrescible substance prepared from the
hides or skins of living creatures, both cold and warm blooded, by
chemical and mechanical treatment. Skins in the raw and natural moist
state are readily putrescible, and are easily disintegrated by bacterial
or chemical action, and if dried in this condition become harsh, horny
and intractable. The art of the leather manufacturer is principally
directed to overcoming the tendency to putrefaction, securing suppleness
in the material, rendering it impervious to and unalterable by water,
and increasing the strength of the skin and its power to resist wear and
tear.
Leather is made by three processes or with three classes of substances.
Thus we have (1) tanned leather, in which the hides and skins are
combined with tannin or tannic acid; (2) tawed leather, in which the
skins are prepared with mineral salts; (3) chamoised (shamoyed) leather,
in which the skins are rendered imputrescible by treatment with oils and
fats, the decomposition products of which are the actual tanning agents.
Heavy leathers.
_Sources and Qualities of Hides and Skins._--The hides used in heavy
leather manufacture may be divided into three classes: (1) ox and
heifer, (2) cow, (3) bull. Oxen and heifer hides produce the best
results, forming a tough, tight, solid leather. Cow hides are thin, the
hide itself being fibrous, but still compact, and by reason of its
spread or area is used chiefly for dressing purposes in the bag and
portmanteau manufacture and work of a similar description. Bull hides
are fibrous; they are largely used for heel lifts, and for cheap
belting, the thicker hides being used in the iron and steel industry.
A second classification now presents itself, viz. the British home
supply, continental (Europe), British colonial, South American, East
Indian, Chinese, &c.
In the British home supply there are three chief breeds: (1) Shorthorns
(Scotch breed), (2) Herefords (Midland breed), (3) Lowland, or Dutch
class. From a tanner's standpoint, the shorthorns are the best hides
procurable. The cattle are exposed to a variable climate in the
mountainous districts of Scotland, and nature, adapting herself to
circumstances, provides them with a thicker and more compact hide; they
are well grown, have short necks and small heads. The Hereford class are
probably the best English hide; they likewise have small heads and
horns, and produce good solid sole leather. The Lowland hides come
chiefly from Suffolk, Kent and Surrey; the animals have long legs, long
necks and big heads. The hides are usually thin and spready. The hides
of the animals killed for the Christmas season are poor. The animals
being stall-fed for the beef, the hides become distended, thin and
surcharged with fat, which renders them unsuitable for first-class work.
The continental supply may be divided into two classes: (1) Hides from
hilly regions, (2) hides from lowlands. All animals subject to strong
winds and a wide range of temperatures have a very strong hide, and for
this reason those bred in hilly and mountainous districts are best. The
hides coming under heading No. 1 are of this class, and include those
from the Swiss and Italian Alps, Bavarian Highlands and Pyrenees, also
Florence, Oporto and Lisbon hides. They are magnificent hides, thick,
tightly-built, and of smooth grain. The butt is long and the legs short.
A serious defect in some of these hides is a thick place on the neck
caused by the yoke; this part of the hide is absolute waste. Another
defect, specially noticeable in Lisbon and Oporto hides, is goad marks
on the rump, barbed wire scratches and warbles, caused by the gadfly.
Those hides coming under heading No. 2 are Dutch, Rhine valley, Danish,
Swedish, Norwegian, Hungarian, &c. The first three hides are very
similar; they are spready, poorly grown, and are best used for bag and
portmanteau work. Hungarian oxen are immense animals, and supply a very
heavy bend. Swedish and Norwegian hides are evenly grown and of good
texture; they are well flayed, and used a great deal for manufacturing
picker bands, which require an even leather.
New Zealand, Australian and Queensland hides resemble good English. A
small quantity of Canadian steers are imported; these are generally
branded.
Chinese hides are exported dry, and they have generally suffered more or
less from peptonization in the storing and drying; this cannot be
detected until they are in the pits, when they fall to pieces.
Anglos are imported as live-stock, and are killed within forty-eight
hours. They come to Hull, Birkenhead, Avonmouth and Deptford from
various American ports, and usually give a flatter result than English,
the general quality depending largely on whether the ship has had a good
voyage or not.
Among South American hides, Liebig's slaughter supply the best; they are
thoroughly clean and carefully trimmed and flayed. They come to London,
Antwerp and Havre, and except for being branded are of first-class
quality. Second to the Liebig slaughter come the Uruguay hides.
East Indian hides are known as kips, and are supposed to be, and should
be, the hides of yearling cattle. They are now dressed to a large extent
in imitation of box calf, being much cheaper. They come from a small
breed of ox, and have an extremely tight grain; the leather is not so
soft as calf.
Calf-skins are largely supplied by the continent. They are soft and
pliant, and have a characteristically fine grain, are tight in texture
and quite apart from any other kind of skin.
Light leathers.
The most valuable part of a sheepskin is the wool, and the value of the
pelt is inversely as the value of the wool. Pure Leicester and Norfolk
wools are very valuable, and next is the North and South Downs, but the
skins, i.e. the pelts, of these animals are extremely poor. Devon and
Cheviot cross-bred sheep supply a fair pelt, and sometimes these sheep
are so many times crossed that it is quite impossible to tell what the
skin is. Welsh skins also supply a good tough pelt, though small. Indian
and Persian sheepskins are very goaty, the herds being allowed to roam
about together so much. The sheepskin is the most porous and
open-textured skin in existence, as also the most greasy one; it is
flabby and soft, with a tight, compact grain, but an extremely loose
flesh. Stillborn lambs and lambs not over a month old are worth much
more than when they have lived for three months; they are used for the
manufacture of best kid gloves, and must be milk skins. Once the lambs
have taken to grass the skins supply a harsher leather.
The best goat-skins come from the Saxon and Bavarian Highlands, Swiss
Alps, Pyrenees, Turkey, Bosnia, Southern Hungary and the Urals. The
goats being exposed to all winds yield fine skins. A good number come
from Argentina and from Abyssinia, the Cape and other parts of Africa.
Of all light leathers the goat has the toughest and tightest grain; it
is, therefore, especially liked for fancy work. The grain is rather too
bold for glacé work, for which the sheep is largely used.
The seal-skin, used largely for levant work, is the skin of the
yellow-hair seal, found in the Northern seas, the Baltic, Norway and
Sweden, &c. The skin has a large, bold, brilliant grain, and being a
large skin is much used for upholstery and coach work, like the Cape
goat. It is quite distinct from the fur seal.
Porpoise hide is really the hide of the white whale; it is dressed for
shooting, fishing and hunting boots. Horse hide is dressed for light
split and upper work; being so much stall-fed it supplies only a thin,
spready leather. The skins of other Equidae, such as the ass, zebra,
quagga, &c. are also dressed to some small extent, but are not important
sources.
_Structure of Skin._--Upon superficial inspection, the hides and skins
of all mammalia appear to be unlike each other in general structure,
yet, upon closer examination, it is found that the anatomical
structure of most skins is so similar that for all practical purposes
we may assume that there is no distinction (see SKIN AND
EXO-SKELETON). But from the practical point of view, as opposed to the
anatomical, there are great and very important differences, such as
those of texture, thickness, area, &c.; and these differences cause a
great divergence in the methods of tanning used, almost necessitating
a distinct tannage for nearly every class of hide or skin.
The skins of the lower animals, such as alligators, lizards, fish and
snakes, differ to a large extent from those of the mammalia, chiefly
in the epidermis, which is much more horny in structure and forms
scales.
The skin is divided into two distinct layers: (1) the epidermis or
epithelium, i.e. the cuticle, (2) the corium derma, or cutis, i.e. the
true skin. These two layers are not only different in structure, but
are also of entirely distinct origin. The epidermis again divides
itself into two parts, viz. the "horny layer" or surface skin, and the
_rete Malpighi_, named after the Italian anatomist who first drew
attention to its existence. The _rete Malpighi_ is composed of living,
soft, nucleated cells, which multiply by division, and, as they
increase, are gradually pushed to the surface of the skin, becoming
flatter and drier as they near it, until they reach the surface as
dried scales. The epidermis is thus of cellular structure, and more or
less horny or waterproof. It must consequently be removed together
with the hair, wool or bristles before tannage begins, but as it is
very thin compared with the corium, this matters little.
The hair itself does not enter the corium, but is embedded in a sheath
of epidermic structure, which is part of and continuous with the
epidermis. It is of cellular structure, and the fibrous part is
composed of long needle-shaped cells which contain the pigment with
which the hair is coloured. Upon removal of the hair some of these
cells remain behind and colour the skin, and this colour does not
disappear until these cells are removed by scudding. Each hair is
supplied with at least two fat or sebaceous glands, which discharge
into the orifice of the hair sheath; these glands impart to the hair
that natural glossy appearance which is characteristic of good health.
The hair bulb (b, fig. 1) consists of living nucleated cells, which
multiply rapidly, and, like the _rete Malpighi_, cause an upward
pressure, getting harder at the same time, thereby lengthening the
hair.
The hair papilla (a, fig. 1) consists of a globule of the corium or
true skin embedded in the hair bulb, which by means of blood-vessels
feeds and nourishes the hair. Connected with the lower part of each
hair is an oblique muscle known as the arrector or erector pili, seen
at k, fig. 1; this is an involuntary muscle, and is contracted by
sudden cold, heat or shock, with an accompanying tightening of the
skin, producing the phenomenon commonly known as "goose flesh." This
is the outcome of the contracted muscle pulling on the base of the
hair, thereby giving it a tendency to approach the vertical, and
producing the simultaneous effect of making the "hair stand on end."
The sudoriferous or sweat glands (R, fig. 1) consist of long
spiral-like capillaries, formed from the fibres of the connective
tissue of the corium. These glands discharge sometimes directly
through the epidermis, but more often into the orifice of the
hair-sheath.
The epidermis is separated from the corium by a very important and
very fine membrane, termed the "hyaline" or "glassy layer," which
constitutes the actual grain surface of a hide or skin. This layer is
chemically different from the corium, as if it is torn or scratched
during the process of tanning the colour of the underlying parts is
much lighter than that of the grain surface.
[Illustration: FIG. 1.
a, Hair papilla.
b, Hair bulb.
c, Hair sheath showing epidermic structure.
d, Dermic coat of hair sheath.
e, Outer root sheath.
f, Inner root sheath.
g, Hair cuticle.
h, Hair.
J, Sebaceous glands.
k, Erector pili.
m, Sweat ducts.
n and _p_, Epidermis.
n, Rete Malpighi.
p, Horny layer.
R, Sweat or sudoriferous gland.
S, Opening at sweat duct.]
The corium, unlike the epidermis, is of fibrous, not cellular
structure; moreover, the fibres do not multiply among themselves, but
are gradually developed as needed from the interfibrillar substance, a
semi-soluble gelatinous modification of the true fibre. This
interfibrillar substance consequently has no structure, and is
prepared at any time on coming into contact with tannin to form
amorphous leather, which fills what would in the absence of this
substance be interfibrillar spaces. The more of this matter there is
present the more completely will the spaces be filled, and the more
waterproof will be the leather. An old bull, as is well known,
supplies a very poor, soft and spongy leather, simply because the hide
lacks interfibrillar substance, which has been sapped up by the body.
The fibres are, therefore, separated by interfibrillar spaces, which
on contact with water absorb it with avidity by capillary attraction.
But a heifer hide or young calf supplies the most tight and waterproof
leather known, because the animals are young, and having plenty of
nourishment do not require to draw upon and sap the interfibrillar
substance with which the skin is full to overflowing.
The corium obtains its food from the body by means of lymph ducts,
with which it is well supplied. It is also provided with nodules of
lymph to nourish the hair, and nodules of grease, which increase in
number as they near the flesh side, until the net skin, _panniculus
adiposus_, or that which separates the corium from meat proper, is
quite full with them.
The corium is coarse in the centre of the skin where the fibres, which
are of the kind known as white connective tissue, and which exist in
bundles bound together with yellow elastic fibres, are loosely woven,
but towards the flesh side they become more compact, and as the
hyaline layer is neared the bundles of fibres get finer and finer, and
are much more tightly interwoven, until finally, next the grain
itself, the fibres no longer exist in bundles, but as individual
fibrils lying parallel with the grain. This layer is known as the
_pars papillaris_. The bundles of fibre interweave one another in
every conceivable direction. The fibrils are extremely minute, and are
cemented together with a medium rather more soluble than themselves.
There are only two exceptions to this general structure which need be
taken into account. Sheep-skin is especially loosely woven in the
centre, so much so that any carelessness in the wet work or sweating
process enables one to split the skin in two by tearing. This
loosely-woven part is full of fatty nodules, and the skin is generally
split at this part, the flesh going for chamois leather and the grain
for skivers. The other notable exception is the horse hide, which has
a third skin over the loins just above the kidneys, known as the crup;
it is very greasy and tight in structure, and is used for making a
very waterproof leather for seamen's and fishermen's boots. Pig-skin,
perhaps, is rather peculiar, in the fact that the bristles penetrate
almost right through the skin.
_Tanning Materials._--Tannin or tannic acid is abundantly formed in a
very large number of plants, and secreted in such diverse organs and
members as the bark, wood, roots, leaves, seed-pods, fruit, &c. The
number of tannins which exists has not been determined, nor has the
constitution of those which do exist been satisfactorily settled. As
used in the tanyard tannin is present both in the free state and
combined with colouring matter and accompanied by decomposition
products, such as gallic acid or phlobaphenes (anhydrides of the
tannins), respectively depending upon the series to which the tannin
belongs. In whatever other points they differ, they all have the
common property of being powerfully astringent, of forming insoluble
compounds with gelatine or gelatinous tissue, of being soluble in
water to a greater or lesser extent, and of forming blacks (greenish
or bluish) with iron. Pyrogallol tannins give a blue-black coloration
or precipitate with ferric salts, and catechol tannins a green-black;
and whereas bromine water gives a precipitate with catechol tannins,
it does not with pyrogallol tannins. There are two distinctive classes
of tannins, viz. catechol and pyrogallol tannins. The materials
belonging to the former series are generally much darker in colour
than those classified with the latter, and moreover they yield reds,
phlobaphenes or tannin anhydrides, which deposit on or in the leather.
Pyrogallol tannins include some of the lightest coloured and best
materials known, and, speaking generally, the leather produced by them
is not so harsh or hard as that produced with catechol tannins. They
decompose, yielding ellagic acid (known technically as "bloom") and
gallic acid; the former has waterproofing qualities, because it fills
the leather, at the same time giving weight.
It has been stated, and perhaps with some truth, that leather cannot
be successfully made with catechol tannins alone; pyrogallol tannins,
however, yield an excellent leather; but the finest results are
obtained by blending the two.