or disappearance of one phase of shell-formation before a later one is entered upon.

The development of the aquatic Pulmonata from the egg offers considerable facilities for study, and that of Limnaeus has been elucidated by E. R. Lankester, whilst H. Rabl has with remarkable skill applied the method of sections to the study of the minute embryos of Planorbis. The chief features in the development of Limnaeus are exhibited in fig. 60. There is not a very large amount of food-material present in the egg of this snail, and accordingly the cells resulting from division are not so unequal as in many other cases. The four cells first formed are of equal size, and then four smaller cells are formed by division of these four so as to lie at one end of the first four (the pole corresponding to that at which the "directive corpuscles" are extruded and remain). The smaller cells now divide and spread over the four larger cells; at the same time a space-the cleavage cavity or blastocoel-forms in the centre of the mulberry-like mass. Then the large cells recommence the process of division and sink into the hollow of the sphere, leaving an elongated groove, the blastopore, on the surface. The invaginated cells (derived from the division of the four big cells) form the endoderm or arch-enteron; the outer cells are the ectoderm. The blastopore now closes along the middle part of its course, which coincides

ng, Cerebral nerve-ganglion. re, Stiebel's canal (left side), probably an embryonic nephridium. sk, The primitive shell-sac or shell-gland.

pi, The rectal peduncle or

attachment to the ectoderm is coincident with the

hindmost extremity of the elongated blastopore of fig. 3. C.

ge, Mesoblastic (skeletotrophic and muscular) cells investing gs, the bilobed archenteron or lateral vesicles of invaginated endoderm, whichwill develop into liver. The foot.

pedicle of invagination; its f. in position with the future "foot." One end of the blastopore becomes nearly closed, and an ingrowth of ectoderm takes place around it to form the stomodaeum or fore-gut and mouth. The other extreme end closes, but the invaginated endoderm cells remain in continuity with this extremity of the blastopore, and form the "rectal peduncle " or "pedicle of invagination" of Lankester, although the endoderm cells retain no contact with the middle region of the now closed-up blastopore. The anal opening forms at a late period by a very short ingrowth or proctodaeum coinciding with the blind termination of the rectal peduncle (fig. 60, pi).

The body-cavity and the muscular, fibrous and vascular tissues are traced partly to two symmetrically disposed mesoblasts," which bud off from the invaginated arch-enteron, partly to cells derived from the ectoderm, which at a very early stage is connected by long processes with the invaginated endoderm. The external form of the embryo goes through the same changes as in other Gastropods, and is not, as was held previously to Lankester's observations, exceptional. When the middle and hinder regions of the blastopore are closing in, an equatorial ridge of ciliated cells is formed, converting the embryo into a typical trochosphere.

The foot now protrudes below the mouth, and the post-oral hemisphere of the trochosphere grows more rapidly then the anterior or velar area. The young foot shows a bilobed form. Within the velar area the eyes and the cephalic tentacles commence to rise up, and on the surface of the post-oral region is formed a cap-like shell and an encircling ridge, which gradually increases in prominence and becomes the freely depending mantle-skirt. The outline of the velar

area becomes strongly emarginated and can be traced through the more mature embryos to the cephalic lobes or labial processes of the adult Limnaeus (fig. 61).

The increase of the visceral dome, its spiral twisting, and the gradual closure of the space overhung by the mantle-skirt so as to

FIG. 61.-A, B, C. Three views of Limnaeus stagnalis, in order to show the persistence of the larval velar area v, as the circum-oral lobes of the adult. m, Mouth; f, foot;v, velar area, the margin y corresponding with the ciliated band which demarcates the velar area or velum of the embryo Gastropod (see fig. 4, D, E, F, H, I, v). (Original.)

convert it into a lung-sac with a small contractile aperture, belong to stages in the development later than any represented in our figures. We may now revert briefly to the internal organization at a period when the trochosphere is beginning to show a prominent foot growing out from the area where the mid-region of the elongated blastopore was situated, and having therefore at one end of it the mouth and at the other the anus. Fig. 60 represents such an embryo under slight compression as seen by transmitted light. The ciliated band of the left side of the velar area is indicated by a line extending from v tov; the foot f is seen between the pharynx ph and the pedicle of invagination pi. The mass of the arch-enteron or invaginated endodermal sac has taken on a bilobed form, and its cells are swollen (gs and tge). This bilobed sac becomes entirely the liver in the adult; the intestine and stomach are formed from the pedicle of invagination, whilst the pharynx, oesophagus and crop form from the stomodaeal invagination ph. To the right (in the figure) of the rectal peduncle is seen the deeply invaginated shell-gland ss, with a secretion sh protruding from it. The shell-gland is destined in Limnaeus to become very rapidly stretched out, and to disappear. Farther up, within the velar area, the rudiments of the cerebral nerve-ganglion ng are seen separating from the ectoderm. A remarkable cord of cells having a position just below the integument occurs on each side of the head. In the figure the cord of the left side is seen, marked-re. This paired organ consists of a string of cells which are perforated by a duct opening to the exterior and ending internally in a flame-cell. Such cannulated cells are characteristic of the nephridia of many worms, and the organs thus formed in the embryo Limnaeus are embryonic nephridia. The most important fact about them is that they disappear, and are in no way connected with the typical nephridium of the adult. In reference to their first observer they were formerly called "Stiebel's canals." Other Pulmonata possess, when embryos, Stiebel's canals in a more fully developed state, for instance, the common slug Limax. Here too they dis

appear during embryonic life. Similar larval nephridia occur in other Gastropoda. In the marine Streptoneura they are ectodermic projections which ultimately fall off; in the Opisthobranchs they are closed pouches; in Paludina and Bithynia they are canals as in Pulmonata.

Marine Pulmonala.-Whilst the Pulmonata are essentially a terrestrial and fresh-water group, there is one genus of slug-like

FIG. 62.-Oncidium tonganum, a littoral Pulmonate, found on the shores of the Indian and Pacific Oceans (Mauritius, Japan). Pulmonates which frequent the sea-coast (Oncidium, fig. 62). Karl Semper has shown that these slugs have, in addition to the usual pair of cephalic eyes, a number of eyes developed upon the dorsal integument. These dorsal eyes are very perfect in elaboration, possessing lens, retinal nerve-end cells, retinal pigment and optic nerve. Curiously enough, however, they differ from the cephalic Molluscan eye in the fact that, as in the vertebrate eye, the filaments of the optic nerve penetrate the retina, and are connected with the

surfaces of the nerve-end cells nearer the lens instead of with the opposite end. The significance of this arrangement is not known, but it is important to note, as shown by V. Henson, S. J. Hickson and others, that in the bivalves Pecten and Spondylus, which also have eyes upon the mantle quite distinct from typical cephalic eyes, there is the same relationship as in Oncidiidae of the optic nerve to the retinal cells. In both Oncidiidae and Pecten the pallial eyes have probably been developed by the modification of tentacles, such as coexist in an unmodified form with the eyes. The Oncidiidae are, according to K. Semper, pursued as food by the leaping fish Periophthalmus, and the dorsal eyes are of especial value to them in aiding them to escape from this enemy.

Sub-order 1.-BASOMMATOPHORA. Pulmonata with an external shell. The head bears a single pair of contractile but not invaginable tentacles, at the base of which are the eyes. Penis at some distance from the female aperture, except in Amphibola and Siphonaria. All have an osphradium, except the Auriculidae, which are terrestrial, and it is situated outside the pallial cavity in those forms in which water is not admitted into the lung. There is a veliger stage in development, but the velum is reduced.

Fam. 1.-Auriculidae. Terrestrial and usually littoral; genital duct monaulic, the penis being connected with the aperture by an open or closed groove; shell with a prominent spire, the internal partitions often absorbed and the aperture denticulated. Auricula. Cassidula. Alexia. Melampus. Carychium, terrestrial, British. Scarabus. Leuconia, British. Blauneria. Pedipes.

Fam. 2. Otinidae. Shell with short spire, and wide oval aperture; tentacles short. Olina, British. Camptonyx, terrestrial. Fam. 3.-Amphibolidae. Shell spirally coiled; head broad, without prominent tentacles; foot short, operculated; marine. Amphibola.

Fam. 4.-Siphonariidae. Visceral mass and shell conical; tentacles atrophied; head expanded; genital apertures contiguous; marine animals, with an aquatic pallial cavity containing secondary branchial laminae. Siphonaria. Fam. 5.-Gadiniidae. Visceral mass and shell conical; head flattened; pallial cavity aquatic, but without a branchia; genital apertures separated. Gadinia.

Fam. 6.-Chilinidae. Shell ovoid, with short spire, wide aperture and folded columella; inferior pallial lobe thick; visceral commissure still twisted. Chilina.

Fam. 7.-Limnaeidae. Shell thin, dextral, with prominent spire and oval aperture; no inferior pallial lobe. Limnaea, British. Amphipeplea, British.

Fam. 8.-Pompholygidae. Shell dextral, hyperstrophic, animal sinistral. Pompholyx. Choanomphalus.

Fam. 9.-Planorbidae. Visceral mass and shell sinistral; inferior pallial lobe very prominent, and transformed into a branchia, Planorbis, British. Bulinus. Miratesta.

Fam. 10.-Ancylidae. Shell conical, not spiral; inferior pallial lobe transformed into a branchia. Ancylus, British. Latia. Grundlachia.

Fam. 11.-Physidae. Visceral mass and shell sinistrally coiled; shell thin, with narrow aperture; no inferior pallial lobe. Physa, British. Aplexa, British.

Sub-order 2.-STYLOMMATOPHORA. Pulmonata with two pairs of tentacles, except Janellidae and Vertigo; these tentacles are invaginable, and the eyes are borne on the summits of the posterior pair. Male and female genital apertures open into a common vestibule, except in Vaginulidae and Oncidiidae. Except in Oncidium, there is no longer a veliger stage in development.

or

Tribe 1.-HOLOGNATHA. Jaw simple, without a superior appendage. Fam. 1.-Selenitidae. Radula with elongated and pointed teeth, like those of the Agnatha; a jaw present. Plutonia. Trigonochlamys. Fam. 2.-Zonitidae. Shell external, smooth, heliciform flattened; radula with pointed marginal teeth. Zonites, British. Ariophanta. Orpiella. Vitrina. Helicarion. Fam. 3.-Limacidae. Shell internal. Limax, British. Parma cella. Urocyclus. Parmarion. Amalia. Agriolimax. Mesolimax. Monochroma. Paralimax. Metalimax. Fam. 4.-Philomycidae. No shell; mantle covers the whole surface of the body; radula with squarish teeth. Philomycus. Fam. 5.-Ostracolethidae. Shell largely chitinous, not spiral, its calcareous apex projecting through a small hole in the mantle. Ostracolethe. Fam. 6.-Arionidae. Shell internal, or absent; mantle restricted to the anterior and middle part of the body; radula with squarish teeth. Arion, British. Geomalacus. Áriolimax. Anadenus. Fam. 7.-Helicidae. Shell with medium spire, external or partly covered by the mantle; genital aperture below the right posterior tentacle; genital apparatus generally provided with a dart-sac and multifid vesicles. Helix, British. Bulimus. Hemphillia. Berendtia. Cochlostyla. Rhodea.. Fam. 8.-Endodontidae. Shell external, spiral, generally ornamented with ribs; borders of aperture thin and not reflected; radula with square teeth; genital ducts without accessory

organs. Endodonta. Punctum. Sphyradium. Laoma. Pyra midula.

Fam. 9.-Orthalicidae. Shell external, ovoid, the last whorl swollen, aperture oval with a simple border; radular teeth in oblique rows. Orthalicus.

Fam. 1o.-Bulimulidae. Jaw formed of folds imbricated externally and meeting at an acute angle near the base. Bulimulus. Pellella. Amphibulimus.

Fam. 11.-Cylindrellidae. Shell turriculated, with numerous whorls, the last more or less detached. Cylindrella. Fam. 12.-Pupidae. Shell external, with clongated spire and numerous whorls, aperture generally narrow; male genital duct without multifid vesicles. Pupa, British. Eucalodium. Vertigo, British. Buliminus, British. Clausilia, British. Balea. Zospeum. Megaspira. Strophia. Anostoma. Fam. 13.-Stenogyridae. Shell elongated, with a more or less obtuse summit; aperture with a simple border. Achatina. Stenogyra. Ferussacia, British. Cionella. Caecilianella. Azeca. Opras.

Fam. 14. Helicteridae. Shell bulimoid, dextral or sinistral; radular teeth, expanded at their extremities and multicuspidate. Helicter. Tornatellina.

Tribe 2.-AGNATHA. No jaws; teeth narrow and pointed; . carnivorous.

Fam. 1.-Oleacinidae. Shell oval, elongated, with narrow aper ture; neck very long; labial palps prominent. Oleacina (Glandina). Streptostyla.

Fam. 2.-Testacellidae. Shell globular or auriform, external or partly covered by the mantle. Streptaxis. Gibbulina. Aerope. Rhytida. Daudebardia. Testacella. Chlamydophorus. Schizo glossa.

Fam. 3. Rathouisiidae. No shell, a carinated mantle covering the whole body; male and female apertures distant, the female near the anus. Rathouisia. Atopos.

Tribe 3.-ELASMOGNATHA. Jaw with a well-developed dorsal appendage. Fam. I.-Succineidae. Anterior tentacles much reduced; male and female apertures contiguous but distinct; shell thin, spiral, with short spire. Succinea, British. Homalonyx. Hyalimax. Neohyalimax.

Fam. 2.-Janellidae. Limaciform, with internal rounded shell; mantle very small and triangular; pulmonary chamber with tracheae; no anterior tentacles. Janella. Aneitella. Aneilca. Triboniophorus. Tribe 4.

DITREMATA. Male and female apertures distant. Fam. 1-Vaginulidae. No shell; limaciform; terrestrial; female aperture on right side in middle of body; anus posterior. Vaginula.

Fam. 2.-Oncidiidae. No shell; limaciform; littoral; female aperture posterior, near anus; a reduced pulmonary cavity with a distinct aperture. Oncidium. Oncidiella, British.

Peronia.

AUTHORITIES.-L. Boutan, "La Cause principale de l'asymétrie des mollusques gastéropodes," Arch. de zool. expér. (3), vii. (1899); A. Lang, Versuch einer Erklärung der Asymmetrie der Gastropoder,' Vierteljahrsschr. naturforsch. Gesellschaft, Zürich, 36 (1892); A. Robert, Recherches sur le développement des Troques," Arch. de zool. expér. (3), x. (1903); P. Pelseneer, "Report on the Pteropoda," Zool. "Challenger Expedit. pts. lviii., lxv., lxvi. (1887, 1888); P. Pelsencer, "Protobranches aériens et Pulmonés branchi fères," Arch. de biol. xiv. (1895); W. A. Herdman, "On the Structure and Functions of the Cerata or Dorsal Papillae in some Nudibranchiate Mollusca," Quart. Journ. Mic. Sci. (1892): J. T. Cunning ham, "On the Structure and Relations of the Kidney in Aplysia,' Mitt. Zool. Stat. Neapel, iv. (1883); Böhmig,“Zur feineren Anatomie von Rhodope veranyi, Kölliker," Zeitschr. f. wiss. Zool. vol. lvi. (1893). TREATISES.-S. P. Woodward, Manual of the Mollusca (2nd ed., with appendix, London, 1869); E. Forbes and S. Hanley, History of British Mollusca (4 vols., London, 1853); Alder and Hancock, Monograph of British Nudibranchiale Mollusca (London, Roy. Society, 1845); P. Pelseneer, Mollusca. Treatise on Zool., edited by E. Ray Lankester, pt. v. (1906); E. Ray Lankester, "Mollusca,' debted. in 9th ed. of this Encyclopaedia, to which this article is much in(J T. C.)

GASTROTRICHA, a small group of fairly uniform animals which live among Rotifers and Protozoa at the bottom of ponds and marshes, hiding amongst the recesses of the algae and sphagnum and other fresh-water plants and eating organic débris and Infusoria. They are of minute size varying from onesixtieth to one-three-hundredth of an inch, and they move by means of long cilia. Two ventral bands composed of regular transverse rows of cilia are usually found. The head bears some especially large cilia. The cuticle which covers the body is here and there raised into overlapping scales which may be prolonged into bristles. An enlarged, frontal scale may cover the head, and a row of scales separates the ventral ciliated areas from one

Pl

Ke.

Sch

Bo

Mr

να

Se

another, whilst two series of alternating rows cover the back and | side. The body, otherwise circular in section, is slightly flattened ventrally. The mouth is anterior and slightly ventral; it leads into a protrusible pharynx armed with recurved teeth that can be everted. This leads to a muscular oesophagus with a triradiate lumen, which acts as a sucking pump and The ends in a funnel-valve projecting into the stomach. The last named is oval and formed of four rows of large cells; it is separated by a sphincter from the rectum, which opens posteriorly and dorsally. The nitrogenous excretory apparatus consists of a coiled tube on each side of the stomach; internally the tubes end in large flame-cells, and externally by small pores which lie on the edges of the ventral row of scales. A cerebral ganglion rests on the oesophagus and supplies the cephalic cilia and hairs; it is continued some way back as two dorsal nerve trunks. T The sen sense organs are the hairs and bristles and in some species eyes. The muscles are simple and unstriated and for the most part run longitudinally.

Sch VS..

Sa

From Zeitschrift für Wissenschalt Zoologie, vol. xlix. P 200 by permission of Wilhelm Engel

mann.

Chaelonotus maximus, Ehrb., ventral side. (After Zelinka.) Bo, Bristles surrounding

the mouth. ds, Dorsal bristles. hci, Posterior lateral cilia. Ke, Cuticular dome. Mr, Oral cavity.

IT, Lateral sensory hairs.
Pl, Cuticular plates.
Sa, Dorsal bristle of the
basal part.

Sch, Plates.

Se, Lateral bristles. Vb, Point of union of ciliated tract.

Ci, Anterior group of cilia. S, Ventral bristles of the

The two ovaries lie at the level of the juncture of the stomach and rectum. The eggs become very large, sometimes half the length of the mother; they are laid amongst water weeds. The male reproductive system is but little known, a small gland lying between the ovaries has been thought to be a testis, and if it be, the Gastrotricha are hermaphrodite.

Zelinka classifies the group as follows:Sub-order 1.-EUICHTHYDINA with a forked tail.

(i.) Fam. Ichthydidae, without bristles. Genera: Ichthydium, Lepidoderma.

(ii.) Fam. Chaetonotidae, with Chaetonotus,

Genera:

bristles.
Chaetura.
Sub-order 2.-APODINA, tail not
forked. Genera: Dasydytes, Gossea,
Stylochaela.

basal part. The genus Aspidiophorus recently described by Voigt seems in some respects intermediate between Lepidoderma and Chaetonotus. Zelinkia and Philosyrtis are two slightly aberrant forms described by Giard from certain diatomaceous sands. Altogether there must be some forty to fifty described species. The group an isolated one and shows no clear affinities with any of the great phyla. Those that are usually dwelt on are treated with the Rotifers and Nematoda and Turbellaria.

LITERATURE.-A. C. Stokes, The Microscope (Detroit, 1887-1888); C. Zelinka, Zeitschr. wiss. Zool. xlix., 1890, p. 209; M. Voigt, Forschber. Plön. Th. ix., 1904, p. 1; A. Giard, C. R. Soc. Biol. Ivi, 1061 and 1063; E. Daday, Termes. Fuzetek. xxiv. p. 1; F. Zschokke, Denk. Schweiz. Ges. Xxxvii. p. 109; S. Hlava, Zool. Anz. xxviii., 1905, p. 331.1 (A. E. S.)

GATAKER, THOMAS (1574-1654), English divine, was born in London in September 1574, and educated at St John's College, Cambridge. From 1601 to 1611 he held the appointment of preacher to the society of Lincoln's Inn, which he resigned on accepting the rectory of Rotherhithe. In 1642 he was chosen a member of the assembly of divines at Westminster, and annotated for that assembly the books of Isaiah, Jeremiah and Lamentations. He disapproved of the introduction of the Covenant, and declared himself in favour of episcopacy. He was one of the forty-seven London clergymen who disapproved of the

trial of Charles I. He was married four times, and died in July 1654.

His principal works, besides some volumes of sermons are-On the Nature and Use of Lots (1619), a curious treatise which led to his being accused of favouring games of chance; Dissertatio de stylo Novi Testamenti (1648); Cinnus, sive Adversaria miscellanea, in quibus Sacrae Scripturae primo, deinde aliorum scriptorum, locis aliquam multis lux redditur (1651), to which was afterwards sub(1652), which, according to Hallam, is the "earliest edition of any joined Adversaria Posthuma; and his edition of Marcus Antoninus classical writer published in England with original annotations, and, for the period at which it was written, possesses remarkable merit. His collected works were published at Utrecht in 1698,

GATCHINA, a town of Russia, in the government of St Petersburg, 29 m. by rail S. of the city of St Petersburg, in 59°34′ N. and 30° 6' E. Pop. (1860) 9184; (1897) 14,735. It is situated in a flat, well-wooded, and partly marshy district, and on the south side of the town are two lakes. Among its more important buildings are the imperial palace, which was founded in 1770 by Prince Orlov, and constructed according to the plans of the Italian architect Rinaldi; a military orphanage, founded in 1803; and a school for horticulture. Among the few industrial establishments is a porcelain factory, At Gatchina an alliance was concluded between Russia and Sweden on the 29th of October 1799.

GATE, an opening into any enclosure for entrance or exit, capable of being closed by a barrier at will. The word is of wide application, embracing not only the defensive entrance ways into a fortified place, with which this article mainly deals, or the imposing architectural features which form the main entrances to palaces, colleges, monastic buildings, &c., but also the common five-barred barrier which closes an opening into a field. The most general distinction that can be made between "door" and

gate" is that of size, the greater entrance into a court containing other buildings being the "gate," the smaller entrances opening directly into the particular buildings the "doors," or that of construction, the whole entrance way being a "gate" or gateway, the barrier which closes it a 'door." A further distinction is drawn by applying "door' to the solid barriers or " valves" of wood, metal, &c., made in panels and fitted to a framework, and "gate" to an openwork structure, whether of metal or wood (see further DOOR and METAL-WORK). The ultimate origin of the word is obscure; the early forms appear with a palatalized initial letter, still surviving in such dialectical forms as "yate," or in Scots "yett." It is probably connected with the root of "get," in the sense either of "means of access or of "holding," "" receptacle "; cf. Dutch gat, hole. There may be a connexion, however, with "gate," now usually spelled "gait," a manner of walking, but originally a way, passage; cf. Ger. Gasse, narrow street, lane.

The entrance through the enclosing walls of a city or fortification has been from the earliest times a place of the utmost importance, considered architecturally, socially or from the point of view of the military engineer. In the East the "gate" was and still is in many Mahommedan countries the central place of civic life. Here was the seat of justice and of audience, the most important market-place, the spot where men gathered to receive and exchange news. The references in the Bible to the gates of the city in all these varied aspects are innumerable (cf. Gen. xix.

Deut. xxv. 7; Ruth iv. 1; 2 Sam. xix. 8; 2 Kings vii. 1). Later the seat of justice and of government is transferred to the gate of the palace of the king (cf. Dan. ii. 49, and Esther ii. 19), and this use is preserved to-day in the official title of the seat of government of the Turkish empire at Constantinople, the "Sublime Porte," a translation of the Turkish Bab Aliy (bab, gate, and aliy, high). A full account with many modern instances of Eastern customs will be found in Sir Charles Warren's article "Gate" in

The spelling "gait "is confined to this meaning-the only literary one surviving. In the form "gate" it appears dialectally in this sense and in such particular meanings as a right to run cattle on common or private ground or as a passage way in mines. The principal survival is in names of streets in the north and midlands of Castle Gate at Nottingham, Gallow Tree Gate at Leicester, and England and in Scotland, e.g. Briggate at Leeds, Wheeler Gate and Canongate and Cowgate at Edinburgh.

The gates into a walled town or other fortified place were necessarily in early times the chief points on which the attack concentrated, and the features, common throughout the ages, of flanking or surmounting towers and of galleries over the entrance way, are found in the Assyrian gate at Khorsabad (cf. 2 Chron. xxvi. 9; 2 Sam. xviii. 24). With the coming of peaceful times to a city or the removal of the fear of sudden attack, the gateways would take a form adapted more for ready exit and entrance than for defence, though the possibility of defending them was not forgotten. Such city gates often had separate openings for entrance and exit, and again for foot passengers and for vehicles. The Gallo-Roman gate at Autun has four entrances, two just wide enough to admit carriages, and two narrow alleys for foot passengers. A fine example of a Roman city gate, dating from the time of Constantine, is at Trèves. It is four storeys high, with ornamental windows, and decorated with columns on each storey. The two outer wings project beyond the central part, the two entrance ways are 14 ft. wide, and could be closed by doors and a portcullis. The chambers in the storeys above were used for the purposes of civil administration. In more modern times city gateways have often followed the type of the Roman triumphal arch, with a single wide opening and purely ornamental superstructure. On the other hand, the defensive gate formed by an archway entering as it were through a tower has been constantly followed as a type of entrance to buildings of an entirely peaceful character. A fine example of such a gateway, originally built for defence, is at Battle Abbey; this was built by Abbot Retlynge in 1338, when Edward III. granted a licence to fortify and crenellate the abbey. Such gateways are typical of Tudor palaces, as at St James's or at Hampton Court, and are the most common form in the colleges of Oxford and Cambridge. The Tom Gate at Christ Church, Oxford, with its surmounted domed bell tower, or the cupola resting on columns at Queen's College, Oxford, are further examples of the gate architecturally considered.

The changes the fortified gateway has undergone in construction and the varying relative importance it has held in the scheme of defence follow the lines of development taken by the history of FORTIFICATION AND SIEGECRAFT (q.v.). The following is a short sketch of the main stages in its history. A good example of the Roman fortified city gate still remains at Pompeii. Here there is one passage way for vehicles, 14 ft. wide; this is open to the sky. The two footways on either side are arched, with openings in the centre on to the central way. The doors of the gate are on the city side, but a portcullis (cataracta) closed it on the country side. The gateways of the Roman permanent camps (castra stativa) were four in number, the porta praetoria and Decumana at either end, with principalis dextra and sinistra on the side (see also CAMP). At Pevensey (Anderida) a small postern on the north side of the Roman walls was laid bare in 1906-1907, in which the passage curves in the thickness of the wall, and from a width admitting two men abreast narrows so that one alone could block it. Flanking towers or bastions guarded the main entrances, while in front were built outworks, of palisades, &c., to protect it; these were known as procastra or antemuralia, and the entrances to these were placed so that they could be flanked from the main walls.

In the defence of a fortified place the gate had not only to be protected from sudden surprise, but also had to undergo protracted attacks concentrated upon it during a siege. Thus until the coming of gunpowder, the ingenuity of military engineers was exhausted in accumulating the most complicated defences round the gateways, and the strength of a fortified place could be estimated by the fewness of its gates. Viollet-le-Duc (Dict. de l'arch. du moyen âge, s.v. Porte) takes the Narbonne and Aude gates (E. and W.) of Carcassonne as typical instances of this complication. The following brief account of the Narbonne Gate (fig. 1), one of the principal parts of the work on the fortifications begun by Philip the Bold in 1285, will give some idea of the varied means of defence, which may be found individually if

of the middle ages. Two massive towers flanked the actual entrance and were linked across by an iron chain; over the entrance (E) was a machicolation, further added to in time of war by a hoarding of timber; and an outer portcullis fell in front of the heavy iron-lined doors. On to the passage way between the first and second doors opened a square machicolation (G) from which the defenders in the upper chambers of the gate could attack an enemy that had succeeded in breaking through the first entrance or had been trapped by the falling of the first portcullis. Another machicolation (I) opened from the roof in front of the second portcullis and second door. So much for the gate itself; but before an attack could reach that point, the following defences had to be passed: an immense circular barbican (A) protected the entrance across the moat and through the outer enceinte of the city. This entrance was flanked by a masked return of the wall (C), while palisades (P) still further hampered the assailant in his passage across the "lists" to the foot of the gate towers. Here sappers would find themselves exposed to a fire from the loopholes and from the machicolated hoardings above them, while the projecting horns with which The City

001

FIG. 1.-Plan of the Narbonne Gate of the city of Carcassonne. the face of the towers terminated forced them to uncover themselves to a flanking fire from the indents in the main curtain on either side of the towers.

The later history of the gateway is merged in that of modern fortification. The more elaborate the gate defences the greater was the inducement for the besieger to attack the walls, and improvements in methods of siegecraft ultimately compelled the defender to develop the enceinte from its medieval form of a ring wall with flanking towers to the 17th century form of bastions, curtains, tenailles and ravelins, all intimately connected in one general scheme of defence. By Vauban's time there is little to distinguish the position and defences of the gateways from the rest of the fortifications surrounding a town. A road from the country usually entered one of the ravelins, sinking into the glacis, crossing the ditch of the ravelin and piercing the parapet almost at right angles to its proper direction (see fig. 2, which also shows a typical arrangement of minor communications such as ramps and staircases). From the interior of the ravelin it passed across the main ditch to a gate in the curtain of the enceinte. The road was in fact artificially made to wind in such a way that it was kept under fire from the defences throughout, while the part of it inside the works was bent so as to place a covering mass between the enemy's fire and troops using the road for a sortie. Thus the gate itself was merely a barrier against a coup de main and to keep out unauthorized persons. In conditions precluding the making of a breach in the walls, i.e. in surprises and assaults de vive force, the gateway and accompanying drawbridge continue to play their part in the 16th, 17th and 18th centuries, but they seldom or never appear as the objectives of a siege en règle. In Vauban's works, and those of most other engineers, there was generally a postern giving access to the floor of the main ditch, in the centre of the curtain escarp. The gates of Vauban's and later fortresses are strong heavy woodea

doors, and the gateways more or less ornamental archways, exactly as in many private mansions of castellar form. In modern fortresses the gate of a detached fort or an enceinte de sureté is intended purely as a defence against an unexpected rush. The usual method is to have two gates, the outer one a lattice or portcullis of iron bars and the inner one a plate of halfinch steel armour, backed by wood and loopholed. The defenders of the gate can by this arrangement fire from the inner loopholes through the outer gate upon the approaches, and also keep the 'enemy under fire whilst he is trying to force the outer gate

Fig. 2.-Plan of Gate Arrangements of an 18th Century Fortress. itself. The ditches are crossed either by drawbridges or by ramps leading the road down to the floor of the ditch.

The "gate" as a barrier to be removed and as an entrance to be passed is of constant occurrence in figurative language and in symbolical usage. The gates of the temple of Janus (q.v.) at Rome stood open in war and closed in peace. The pylon of ancient Egypt had a symbolical meaning in the Book of the Dead, and religious significance attaches to the torii, one of the outward signs of the Shinto religion in Japan, the Buddhist foran, and to the Chinese pai-loo, the honorific gateways erected to ancestors. The gates of heaven and hell, the gates of death and darkness, the wide and narrow gates that lead to destruction and life (Matt. vii. 13 and 14), are familiar metaphorical phrases in the Bible. In Greek and Roman legend dreams pass through gates of transparent horn. if true, if deceptive and false through opaque gates of ivory (Hom. Od. xix. 560 sq.; Virg. Aen. vi. 893). (C. WE.)

GATEHOUSE. In the second half of the 16th century in England the entrance gateway, which formed part of the principal front of the earlier feudal castles, became a detached feature attached to the mansions only by a wall enclosing the entrance court. The gatehouse then constituted a structure of some importance, and included sometimes many rooms as at Stanway Hall, Gloucestershire, where it measures 44 ft. by 22 ft. and has three storeys; at Westwood, Worcestershire, it had a frontage of 54 ft. with two storeys; and at Burton Agnes, Yorkshire, it was still larger and was flanked by great octagonal towers at the angles and had three storeys. At a later period smaller accommodation was provided so that it virtually became a lodge, but being designed to harmonize with the mansion it presented sometimes a monumental structure. On the continent of Europe the gatehouse forms a much more important building, as it formed part of the town fortifications, where it sometimes defended the passage of a bridge across the stream or moat. There are numerous examples in France and Germany.

GATES, HORATIO (1728-1806), American general, was born at Maldon in Essex, England, in 1728. He entered the English army at an early age, and was rapidly promoted. He accompanied General Braddock in his disastrous expedition against Fort Duquesne in 1755, and was severely wounded in the battle of July 9; and he saw other active service in the Seven Years' War. After the peace of 1763 he purchased an estate in Virginia,

where he lived till the outbreak of the War of Independence in 1775, when he was named by Congress adjutant-general. In 1776 he was appointed to command the troops which had lately retreated from Canada, and in August 1777, as a result of a successful intrigue, was appointed to supersede General Philip Schuyler in command of the Northern Department. In the two battles of Saratoga (q.v.) his army defeated General Burgoyne, who, on the 17th of October, was forced to surrender his whole army. This success was, however, largely due to the previous manœuvres of Schuyler and to Gates's subordinate officers. The intrigues of the Conway Cabal to have Washington superseded by Gates completely failed, but Gates was president for a time of the Board of War, and in 1780 was placed in chief command in the South. He was totally defeated at Camden, S.C., by Cornwallis on the 17th of August 1780, and in December was superseded by Greene, though an investigation into his conduct terminated in acquittal (1782). He then retired to his Virginian estate, whence he removed to New York in 1790, after emancipating his slaves and providing for those who needed assistance. He died in New York on the 10th of April 1806.

GATESHEAD, a municipal, county and parliamentary borough of Durham, England; on the S. bank of the Tyne opposite Newcastle, and on the North Eastern railway. Pop. (1891) 85,692; (1901) 109,888. Though one of the largest towns in the county, neither its streets nor its public buildings, except perhaps its ecclesiastical buildings, have much claim to architectural beauty. The parish church of St Mary is an ancient cruciform edifice surmounted by a lofty tower; but extensive restoration was necessitated by a fire in 1854 which destroyed a considerable part of the town. The town-hall, public library and mechanic's institute are noteworthy buildings. Education is provided by a grammar school, a large day school for girls, and technical and art schools. There is a service of steam trams in the principal streets, and three fine bridges connect the town with Newcastle-upon-Tyne. There are large iron works (including foundries and factories for engines, boilers, chains and cables), shipbuilding yards, glass manufactories, chemical, soap and candle works, brick and tile works, breweries and tanneries. The town also contains a depot of the North Eastern railway, with large stores and locomotive works. Extensive coal mines exist in the vicinity; and at Gateshead Fell are large quarries for grindstones, which are much esteemed and are exported to all parts of the world. Large gas-works of the Newcastle and Gateshead Gas Company are also situated in the borough. The parliamentary borough returns one member. The corporation consists of a mayor, 9 aldermen, and 27 councillors. Area, 3132 acres.

Gateshead (Gateshewed) probably grew up during late Saxon times, the mention of the church there in which Bishop Walcher was murdered in 1080 being the first evidence of settlement. The borough probably obtained its charter during the following century, for Hugh de Puiset, bishop of Durham (1153-1195), confirmed to his burgesses similar rights to those of the burgesses of Newcastle, freedom of toll within the palatinate and other privileges. The bishop had a park here in 1348, and in 1438 Bishop Nevill appointed a keeper of the " tower.". The position of the town led to a struggle with Newcastle over both fishing and trading rights. An inquisition of 1322 declared that the water of the Tyne was divided into three parts: the northern, belonging to Northumberland; the southern to Durham; and the central, common to all. At another inquisition held in 1336 the men of Gateshead claimed liberty of trading and fishing along the coast of Durham, and freedom to sell their fish where they would. In 1552, on the temporary extinction of the diocese of Durham, Gateshead was attached to Newcastle, but in 1554 was regranted to Bishop Tunstall. As compensation the bishop granted to Newcastle, at a nominal rent, the Gateshead salt-meadows, with rights of way to the High Street, thus abolishing the toll previously paid to the bishop. During the next century Bishop Tunstall's successors incorporated nearly all the various trades of Gateshead, and Cromwell continued this policy. The town government during this period was by