[1] See Menant, _Bibliothèque du palais de Ninive_ (Paris, 1880).
[2] Grote, _History of Greece_, iv. 37, following Becker.
[3] Ritschl, _Die alexandrinischen Bibliotheken_, p. 22; _Opusc.
phil._ i. § 123.
[4] _N.A._ vi. 17.
[5] _De tranq. an._ 9.
[6] Parthey (_Alexandrinisches Museum_) assigns topographical reasons
for doubting this story.
[7] Some of the authorities have been collected by Parthey, _op.
cit._
[8] The oldest catalogue of a western library is that of the
monastery of Fontanelle in Normandy compiled in the 8th century. Many
catalogues may be found in the collections of D'Achery, Martene and
Durand, and Pez, in the bibliographical periodicals of Naumann and
Petzholdt and the _Centralblatt f. Bibliothekswissenschaft_. The Rev.
Joseph Hunter has collected some particulars as to the contents of
the English monastic libraries, and Ed. Edwards has printed a list of
the catalogues (_Libraries and Founders of Libraries_, 1865, pp.
448-454). See also G. Becker, _Catalogi Bibliothecarum Antiqui_
(1885). There are said to be over six hundred such catalogues in the
Royal Library at Munich. In the 14th century the Franciscans compiled
a general catalogue of the MSS. in 160 English libraries and about
the year 1400 John Boston, a Benedictine monk of Bury, travelled over
England and a part of Scotland and examined the libraries of 195
religious houses (Tanner, _Bibliotheca Brit. Hibern._ 1748). Leland's
list of the books he found during his visitation of the houses in
1539-1545 is printed in his _Collectanea_ (ed. Hearne, 1715, 6
vols.). T. W. Williams has treated Gloucestershire and Bristol
medieval libraries and their catalogues in a paper in the Bristol and
Gloucestershire _Arch. Soc._ vol. xxxi.
[9] This subject has been specially treated by J. Willis Clark in
several works, of which the chief is a masterly volume, _The Care of
Books_ (1901). See also Dom Gasquet, "On Medieval Monastic
Libraries," in his _Old English Bible_ (1897).
[10] Among the Arabs, however, as among the Christians, theological
bigotry did not always approve of non-theological literature, and the
great library of Cordova was sacrificed by Almanzor to his reputation
for orthodoxy, 978 A.D.
[11] _Guide to Librarianship_ by J. D. Brown (1909).
LIBRATION (Lat. _libra_, a balance), a slow oscillation, as of a
balance; in astronomy especially the seeming oscillation of the moon
around her axis, by which portions of her surface near the edge of the
disk are alternately brought into sight and swung out of sight.
LIBYA, the Greek name for the northern part of Africa, with which alone
Greek and Roman history are concerned. It is mentioned as a land of
great fertility in Homer (_Odyssey_, iv. 85), but no indication of its
extent is given. It did not originally include Egypt, which was
considered part of Asia, and first assigned to Africa by Ptolemy, who
made the isthmus of Suez and the Red Sea the boundary between the two
continents. The name Africa came into general use through the Romans. In
the early empire, North Africa (excluding Egypt) was divided into
Mauretania, Numidia, Africa Propria and Cyrenaica. The old name was
reintroduced by Diocletian, by whom Cyrenaica (detached from Crete) was
divided into Marmarica (Libya inferior) in the east, and Cyrenaica
(Libya superior) in the west. A further distinction into Libya interior
and exterior is also known. The former ([Greek: hê entós]) included the
interior (known and unknown) of the continent, as contrasted with the N.
and N.E. portion; the latter ([Greek: hê exô], called also simply Libya,
or _Libyae nomos_), between Egypt and Marmarica, was so called as having
once formed an Egyptian "nome." See AFRICA, ROMAN.
LICATA, a seaport of Sicily, in the province of Girgenti, 24 m. S.E. of
Girgenti direct and 54 m. by rail. Pop. (1901) 22,931. It occupies the
site of the town which Phintias of Acragas (Agrigentum) erected after
the destruction of Gela, about 281 B.C., by the Mamertines, and named
after himself. The river Salso, which flows into the sea on the east of
the town, is the ancient _Himera Meridionalis_. The promontory at the
foot of which the town is situated, the _Poggio di Sant' Angelo_, is the
Ecnomus (_Eknomon_) of the Greeks, and upon its slopes are scanty traces
of ancient structures and rock tombs. It was off this promontory that
the Romans gained the famous naval victory over the Carthaginians in the
spring of 256 B.C., while the plain to the north was the scene of the
defeat of Agathocles by Hamilcar in 310 B.C. The modern town is mainly
important as a shipping port for sulphur.
LICENCE (through the French from Lat. _licentia_, _licere_, to be
lawful), permission, leave, liberty, hence an abuse of liberty,
licentiousness; in particular, a formal authority to do some lawful act.
Such authority may be either verbal or written; when written, the
document containing the authority is called a "licence." Many acts,
lawful in themselves, are regulated by statutory authority, and licences
must be obtained. For the sale of alcoholic liquor see LIQUOR LAWS.
LICHEN (_lichen ruber_), in medical terminology, a papular disease of
the skin, consisting of an eruption in small thickly set, slightly
elevated red points, more or less widely distributed over the body, and
accompanied by slight febrile symptoms.
LICHENS, in botany, compound or dual organisms each consisting of an
association of a higher fungus, with a usually unicellular, sometimes
filamentous, alga. The fungal part of the organism nearly always
consists of a number of the _Discomycetes_ or _Pyrenomycetes_, while the
algal portion is a member of the Schizophyceae (Cyanophyceae or
Blue-green Algae) or of the Green Algae; only in a very few cases is the
fungus a member of the Basidiomycetes. The special fungi which take part
in the association are, with rare exceptions, not found growing
separately, while the algal forms are constantly found free. The
reproductive organs of the lichen are of a typically fungal character,
i.e. are apothecia or perithecia (see FUNGI) and spermogonia. The algal
cells are never known to form spores while part of the lichen-thallus,
but they may do so when separated from it and growing free. The fungus
thus clearly takes the upper hand in the association.
Owing to their peculiar dual nature, lichens are able to live in
situations where neither the alga nor fungus could exist alone. The
enclosed alga is protected by the threads (hyphae) of the fungus, and
supplied with water and salts and, possibly, organic nitrogenous
substances; in its turn the alga by means of its green or blue-green
colouring matter and the sun's energy manufactures carbohydrates which
are used in part by the fungus. An association of two organisms to their
mutual advantage is known as _symbiosis_, and the lichen in botanical
language is described as a symbiotic union of an alga and a fungus. This
form of relationship is now known in other groups of plants (see
BACTERIOLOGY and FUNGI), but it was first discovered in the lichens. The
lichens are characterized by their excessively slow growth and their
great length of life.
Until comparatively recent times the lichens were considered as a group
of simple organisms on a level with algae and fungi. The green (or
blue-green) cells were termed gonidia by Wallroth, who looked upon them
as asexual reproductive cells, but when it was later realized that they
were not reproductive elements they were considered as mere outgrowths
of the hyphae of the thallus which had developed chlorophyll. In 1865 De
Bary suggested the possibility that such lichens as _Collema_, _Ephebe_,
&c., arose as a result of the attack of parasitic Ascomycetes upon the
algae, Nostoc, Chroococcus, &c. In 1867 the observations of Famintzin
and Baranetzky showed that the gonidia, in certain cases, were able to
live outside the lichen-thallus, and in the case of Physcia, Evernia and
Cladonia were able to form zoospores. Baranetzky therefore concluded
that a certain number, if not all of the so-called algae were nothing
more than free living lichen-gonidia. In 1869 Schwendener put forward
the really illuminating view--exactly opposite to that of
Baranetzky--that the gonidia in all cases were algae which had been
attacked by parasitic fungi. Although Schwendener supported this view of
the "dual" nature of lichens by very strong evidence and identified the
more common lichen-gonidia with known free-living algae, yet the theory
was received with a storm of opposition by nearly all lichenologists.
These workers were unable to consider with equanimity the loss of the
autonomy of their group and its reduction to the level of a special
division of the fungi. The observations of Schwendener, however,
received ample support from Bornet's (1873) examination of 60 genera. He
investigated the exact relation of fungus and alga and showed that the
same alga is able to combine with a number of different fungi to form
lichens; thus _Chroolepus umbrinus_ is found as the gonidia of 13
different lichen genera.
The view of the dual nature of lichens had hitherto been based on
analysis; the final proof of this view was now supplied by the actual
_synthesis_ of a lichen from fungal and algal constituents. Rees in 1871
produced the sterile thallus of a _Collema_ from its constituents; later
Stahl did the same for three species. Later Bonnier (1886) succeeded in
producing fertile thalli by sowing lichen spores and the appropriate
algae upon sterile glass plates or portions of bark, and growing them in
sterilized air (fig. 1). Möller also in 1887 succeeded in growing small
lichen-thalli without their algal constituent (gonidia) on nutritive
solutions; in the case of _Calicium_ pycnidia were actually produced
under these conditions.
The thallus or body of the lichen is of very different form in different
genera. In the simplest filamentous lichens (e.g. _Ephebe pubescens_)
the form of thallus is the form of the filamentous alga which is merely
surrounded by the fungal hyphae (fig. 2). The next simplest forms are
gelatinous lichens (e.g. _Collemaceae_); in these the algae are
Chroococcaceae and Nostocaceae, and the fungus makes its way into the
gelatinous membranes of the algal cells and ramifies there (fig. 3). We
can distinguish this class of forms as lichens with a _homoiomerous_
thallus, i.e. one in which the alga and fungus are equally distributed.
The majority of the lichens, however, possess a stratified thallus in
which the gonidia are found as a definite layer or layers embedded in a
pseudo-parenchymatous mass of fungal hyphae, i.e. they are
_heteromerous_ (figs. 8 and 9). Obviously these two conditions may merge
into one another, and the distinction is not of classificatory value.
[Illustration: After Bonnier, from v. Tavel.
From Strasburger's _Lehrbuch der Botanik_, by permission of Gustav
Fischer.
FIG. 1.--_Xanthoria parietina._ By the fusion of the hyphae in the
middle of the mycelium a pseudo-parenchymatous cortical layer has
begun to form.
1, Germinating ascospore (sp) with branching germ-tube applied to the
_Cystococcus_ cells (a).
2, Thallus in process of formation.
sp, Two ascospores.
p, _Cystococcus_ cells.]
In external form the heteromerous thallus presents the following
modifications. (a) The _foliaceous_ (leaf-like) thallus, which may be
either peltate, i.e. rounded and entire, as in _Umbilicaria_, &c., or
variously lobed and laciniated, as in _Sticta_, _Parmelia_, _Cetraria_
(fig. 4), &c. This is the highest type of its development, and is
sometimes very considerably expanded. (b) The _fruticose_ thallus may
be either erect, becoming pendulous, as in _Usnea_ (fig. 5),
_Ramalina_, &c., or prostrate, as in _Alectoria jubata_, var.
_chalybeiformis_. It is usually divided into branches and branchlets,
bearing some resemblance to a miniature shrub. An erect cylindrical
thallus terminated by the fruit is termed a _podetium_, as in
_Cladonia_ (fig. 7). (c) The _crustaceous_ thallus, which is the most
common of all, forms a mere crust on the substratum, varying in
thickness, and may be squamose (in _Squamaria_), radiate (in
_Placodium_), areolate, granulose or pulverulent (in various
_Lecanorae_ and _Lecideae_). (d) The _hypophloeodal_ thallus is often
concealed beneath the bark of trees (as in some _Verrucariae_ and
_Arthoniae_), or enters into the fibres of wood (as in _Xylographa_
and _Agyrium_), being indicated externally only by a very thin film
(figs. 3, 4, 5, 6, 7 and 8). In colour also the thallus externally is
very variable. In the dry and more typical state it is most frequently
white or whitish, and almost as often greyish or greyish glaucous.
Less commonly it is of different shades of brown, red, yellow and
black. In the moist state of the thallus these colours are much less
apparent, as the textures then become more or less translucent, and
the thallus usually prevents the greenish colour of the gonidia (e.g.
_Parmelia Borreri_, _Peltidea aphthosa_, _Umbilicaria pustulata_ and
pulverulent _Lecideae_).
The thallus may be free upon the surface of the substratum (e.g.
_Collema_) or may be fixed more or less closely to it by special
hyphae or rhizoids. These may penetrate but slightly into the
substratum, but the connexion established may be so close that it is
impossible to remove the thallus from the substratum without injury
(e.g. _Physcia_, _Placodium_). In some cases the rhizoids are united
together into larger strands, the _rhizines_.
The typical heteromerous thallus shows on section a peripheral, thin
and therefore transparent, layer, the _cortical layer_, and centrally
a mass of denser tissue the so-called _medullary layer_, between these
two layers is the algal zone or gonidial layer (figs. 8 and 9).
The term _epithallus_ is sometimes applied to the superficial dense
portion of the cortical layer and the term _hypothallus_ to the layer,
when specially modified, in immediate contact with the substratum; the
hypothallus is usually dark or blackish. The cylindrical branches of
the fruticose forms are usually radially symmetrical, but the
flattened branches of these forms and also the thalli of the
foliaceous form show a difference in the cortex of the upper and lower
side. The cortical layer is usually more developed on the side towards
the light, while in many lichens this is the only side provided with a
cortical layer. The podetia of some species of Cladonia possess no
cortical layer at all. The surface of the thallus often exhibits
outgrowths in the form of warts, hairs, &c. The medullary layer, which
usually forms the main part of the thallus, is distinguished from the
cortical layer by its looser consistence and the presence in it of
numerous, large, air-containing spaces.
[Illustration: After Sachs, from De Bary's _Vergleichende Morphologie
und Biologie der Pilze, Mycetozoen und Bacterien_, by permission of
Wilhelm Engelmann.
FIG. 2.--_Ephebe pubescens_, Fr. A branched filiform thallus of
_Stigonema_ with the hyphae of the fungus growing through its
gelatinous membranes. Extremity of a branch of the thallus with a
young lateral branch a; h, hyphae; g, cells of the alga; gs, the apex
of the thallus.]
[Illustration: FIG. 3.--Section of Homoiomerous Thallus of _Collema
conglomeratum_, with _Nostoc_ threads scattered among the hyphae.]
[Illustration: From Strasburger's _Lehrbuch der Botanik_, by permission
of Gustav Fischer.