which there is a railway viaduct. The population in' skins, and copper and brass vessels. The annual out1875 was 12,954.

Hirschberg was in existence in the 11th century, and obtained town rights in 1108 from Boleslaus III. of Poland, It withstood a siege by the Hussites in 1427, and an attack of the imperial troops in 1640. The foundation of its prosperity was laid in the 16th century by the introduction of

the manufacture of linen and veils.

HIRTIUS, AULUS, one of Caesar's chief supporters and most intimate friends. He was with him as legatus in Gaul. After the civil war broke out in 49 B.C., he seems to have been generally stationed in Rome to protect Caesar's interests there. He was a personal friend of Cicero, and used his influence with Caesar in behalf of the orator's brother and nephew. He was nominated along with Pansa by Caesar for the consulship of 43 B.C.; and after the dictator's assassination in March, 44, this honor made him for a short time one of the leading actors in that troubled time. The consuls supported the senatorial party against Antony, and led their armies into Umbria, where Antony was blockading Dec. Brutus in Mutina. On March 27th a double battle was fought: in the first Antony had the upper hand, and Pansa was mortally wounded; and in the second Hirtius completely defeated the enemy, but was himself killed in the subsequent assault on the enemy's camp. Hirtius was perhaps an author: the eighth book of Caesar's commentaries on the Gallic war, which was certainly not written by Cæsar himself, is commonly attributed to him; and the accounts of the Alexandrian, African, and Spanish wars are perhaps also due to his pen.

HISPANIOLA. See HAYTI.

HISSÁR, a British district belonging to the division of the same name, in the lieutenant-governorship of the Punjab, India, lying between 28° 36′ and 29° 49' N. lat., and between 75° 16′ and 76° 22′ E. long. It is bounded on the N. and N. W. by the Patiala state and a small portion of the British district of Sirsa, on the E. and S. by the territory of Jhind and the British district of Rohtak, and on the W. by the deserts of Bikaner. Area, 3539 square miles; population (1868),

484,681.

turn of rough saltpetre is estimated at 450 maunds. The trade of the district centres in Bhawani, where nine lines of traffic converge. The main road, about 50 feet wide, unmetalled, traverses the district, passing through Hansi and Hissár towns; fourteen other roads supply communication. The census of 1868 returned the population at 484,681 (males, 266,847; females, 217,834). The Hindus numbered 373,937; Mahometans, 102,928; Sikhs, 1812; and "others," 6004. There are three municipalities, viz.: Bhawáni, 32,254; Hissár, 14,133; and Hánsi, 13,563. The district police numbered 396 men in 1872-73, and the municipal police 174. In the same year there were 50 schools, with 1729 scholars. The climate of Hissár is very dry; hot westerly winds blow from the middle of March till July. The average rainfall for the six years 1867-68 to 1872-73 was 14.57 inches. The principal diseases are fevers and small-pox. Cholera occasionally breaks out. Skin diseases also are common. Government dispensaries are situated at Bhawani and Hánsi.

Prior to the Mahometan conquest, the semi-desert tract of which Hissár district now forms part was the retreat of Chauhán Rájputs. Towards the end of the 18th century, the Bhattiís of Bhattíána gained ascendency after bloody struggles. To complete the ruin brought on by these confiicts, nature lent her aid in the great famine of 1783. Hissár enforce order till 1810. Early in the mutiny of 1857 Hissár passed nominally to the British in 1803, but they could not was wholly lost for a time to British rule, and all Europeans were either murdered or compelled to fly. The Bhattis rose under their hereditary chiefs, and the majority of the Mahometan population followed their example. Before

Delhi had been recovered the rebels were utterly routed.

HISSAR, municipal town and administrative headquarters of the above district, 29° 9′ 51′′ N. lat., 75° 45′ 55 E. long.; population (1868), 14.133 (Hindus 9211, Mahometans 4805, Sikhs 34, Christians 83). The town is situated on the Western Junna Canal, 102 miles W. of Delhi. It was founded in 1354 by the Emperor Firoz Shah, who constructed the canal to supply it with water; but this fell into decay during the last century, owing to the constant inroads of maraudHissar forms the western border district of the greaters. Hissar was almost completely depopulated durBikaner desert, and consists for the most part of sandy ing the famine of 1783, but was afterwards occupied plains dotted with shrub and brushwood, and broken by the adventurer George Thomas, who built a fort by undulations towards the south, which rise into hills and collected inhabitants. It contains a cattle farm, of rock like islands out of a sea of sand. The Ghaggar both for commissariat purposes and for improving the is its only river, whose supply is uncertain, depending breed of the province; attached is an estate of 43,287 much on the fall of rain in the lower Himálayas; its acres for pasturage. There is an import trade in grain, overflow in times of heavy rain is caught near Fate-ghi, sugar, oil, cotton, tobacco, and English piece hábád and Murakhera by jhils, which dry up in the goods. The municipal revenue in 1875-76 was £1229. hot season. A canal, known as the Western Jumna Canal, crosses the district from east to west, irrigating 54 villages. The soil is in places hard and clayey, and difficult to till; but when sufficiently irrigated it is highly productive. Old mosques and other buildings exist in parts of the district.

Rice is the staple crop of the district. In favorable seasons, cotton is extensively grown in lands irrigated by the Western Jumna Canal. In 1872-73, 1,431,541 acres were under tillage, out of an assessed area of 2,265,428 acres. Hissár produces a breed of milkwhite oxen, 17 or 18 hands in height, which are in great request for the carriages of natives. The district has always been subject to famine. The first calamity of this kind of which we have authentic record was the famine of 1783; since then there have been several more or less serious failures of the crops.

The principal exports are oil-seeds, gram, grains, copper and brass utensils, hides, and a little cotton; the imports-salt, sugar, fine rice, cotton goods of English make, spices, and iron. The exports are double the imports in value. The rural manufactures comprise coarse cotton cloth, vessels made of prepared

The division of Hissar is under a commissioner, and comprises

the three districts of Hissár, Rohtak, and Sirsa, Area, 8478 square miles. Population (1868), 1,232,435,

HISSAR, a state in Central Asia, lying between the meridians of 66° 30′ and 70° E. and the parallels of 39° 15' and 37° N., and dependent on the amir of Bokhara. It forms that part of the basin of the Oxus which lies on the north side of the river, opposite the Afghan province of Balkh. The western prolongation of the Tian Shan, which divides the basin of the Zarafshan from that of the upper Oxus, after rising in one peak to a height of 12,300 feet, bifurcates in 67° 45′ E. long. Its two arms include between them the province of Shahr-i-Sabz, with the towns of Shahr Sabz, Kitab, Yakobagh, and Karchi. The main chain and the southern arm of its bifurcation, sometimes called Kohi-tan, form the N. and N. W. boundaries of Hissar. On the W. it is wholly bounded by the desert; the Oxus limits it on the S. and S. E.; and the states of Karategin and Darwaz complete the boundary on the E. Until 1875 it was one of the least-known tracts of Central Asia, but in that year a Russian expedition from Tashkend traversed and surveyed a great portion of it, and since then successive expeditions have explored various other portions, so that it is now very fairly known. Hissar is traversed from north to south by four important tributaries of the Oxus, viz., the Surkhab or Vaksh, Kafirnihan, Surkhan, and ShirabadDaria, which descend from the snowy mountains to the

north and form a series of fertile valleys, disposed in a from Hissar) contains about 500 houses and a poor fan-shape, within which lie embosomed the principal citadel, and from it there are roads to Badakhshan and towns of Hissar. The two chief roads by which Hissar Kurgan-tepe and Kubadian. These two lie in the valis approached from Bokhara and Russian Turkestan leys of the Vaksh (or Surkhab) and Kafirnihan respectlie through Karchi and Shahr-i-Sabz respectively. ively. Kulab produces wheat in great profusion, and Both these routes unite at Ak-roba, on the crest of the gold is brought thither from the surrounding districts. range between Khuzar and Baisun. There is also a Kubadian is a large, silk-producing town, and is surdifficult route, running through fine forests from Yako- rounded with rice-fields. Formerly the two last-named bagh across the mountains to Sarijui. A little way valleys were densely peopled, and a series of settledown the other side of the mountain chain between ments extended southward from Dehinau, from which Khuzar and Derbend is situated the famous defile town an arik or canal provided the city of Termez with formerly called Kohluga (Mong. "Barrier') and the water. Termez, or Termedh, was an ancient and imIron Gate, but now styled Buzghol-khana or Goat's portant city on the Oxus. After being destroyed by House. This pass is described by the Russians, who Jenghiz Khan and lying for some time in ruins, it rose visited it and were vividly impressed with its solemnity, again into note in the following century, and when visas a huge but narrow chasm in a transverse range, ited by Ibn Batuta, and later by Clavijo, it had grown whose frowning rocks overhang and threaten to choke again into a place of some importance. It is now a the tortuous and gloomy corridor (in places but 5 paces mass of ruins. wide) affording the only exit from the valley. In ancient times it was a vantage-point of much importance, The population of the districts of Hissar and Kulab conand commanded the chief route between Turkestan sists principally of Uzbeks and Tajiks, the former predomiand India. Hwen-Tsang, who passed through it in nating, and as in the valleys of the Sir and Zarafshán, gradually pushing the aborignal Tajiks into the hills. East the 7th century on his way southward, states that of Dushamba the Tajiks are the dominant race. On the there were then two folding doors or gates, cased with banks of the Oxus there are some tribes of Baigush Turkiron and hung with bells, placed across the pass. Cla-mans who work at the ferries, drive sheep, and accompany vijo, the Spanish ambassador to the court of Timur, caravans. Lyuli (gypsies, Jews, Hindus, and Afghans are heard of this when he passed through the defile 800 also to be found in Hissar. But the Uzbeks are the most years after, but the gates had then disappeared. Der- numerous, and their influence is so great that at Bokhara bend, the first inhabited place met with, is a poor vil- of Hissar and Kulab is pleasant, as they are shut in by Hissar is known as Uzbekistan. The climate of the valleys lage in the valley of the Shirabad-Daria, along which mountains to the north and open towards the Oxus to the runs the road to the Oxus and to Afghanistan. Shir- south. Baisun (3410 feet) is the most elevated town. Hissar abad town itself is a place claiming great antiquity. It and Kulab produce in abundance all the cereals and garden has a citadel and three rows of walls, and with its sur- plants indigenous to Central Asia. Cotton is grown in conrounding villages presents the aspect of a flourishing siderable quantities in the district of Shirabad, whence it oasis. There are four ferries over the Oxus in the is exported by way of Khuzar to Karshi. The difficulties of transport would prevent its being brought in any quanShirabad chiefship or district, viz., Chushka-guzar tity from other places. Dehinau, Hissar, and Dushamba (boar's ferry), Patta-kissar, Shur-ab, and Karakamir. export corn and flax to Bokhara. From the vicinity of Baisun, a picturesque Uzbek town considered to be Khuzar is exported rock-salt, and sheep are brought to very healthy, lies on the road from Derbend to Hissar Bokhara and Karshi from all parts of Hissar district, as town. Emerging from the somewhat complex mounwell as from Baljuan, Yurchi, and Afghanistan. A species tain mass which fills up this part of Hissar, the valley of juniper, called archa, is used for timber. Salt is found of the Surkhan is reached. This large river is formed at Bash-kurd, in the mountains of Hazret-Imam, and at other places. There are numerous brine springs in various by several affluents from the snowy range to the north, quarters, indicating generally an inexhaustible supply of one of which, the Tupalan, formerly gave its name to rock-salt. Auriferous sand has been discovered in the the whole stream. The valley in its upper part is be- Vaksh, and the inhabitants wash the sands after the floods tween 40 and 45 miles wide; the banks of the river are in spring. Merchandise is conveyed by means of camels, flat and reed-grown, and are frequented by wild hogs mules, and horses from Hissar to Karshi and Bokhara. Not and a few tigers. The Surkhan valley is highly culti- a single wagon is to be found in the district, and the vated, especially in its upper portion, where the villages wooden arba is not even known there. Politically, Hissar now consists of seven sub-districts, governed by begs, Shirare crowded. It supplies Bokhara with corn and sheep, abad, Baisun, Dehinau, Yurchi, Hissar, Kurgan-tepe, and but its chief products are rice and flax. When Hissar Kubadian; and Kulab of two, Baljuan and Kulab. The was independent the valley of the Surkhan was always fact of the chief route between the Russian and British its political centre, the town of Hissar being simply an possessions in Asia lying through Hissar has served of late outlying fortress. Passing by four fortified towns, years to bring it into prominence, and will always invest it with a certain importance. Dehinau, Sarijui, Regar, and Karatagh, all in the basin of the Surkhan, Hissar (= fort) claims notice. Its position at the entrance of the Pavi-dul-dul defile commanded the entrance into the fertile valleys of the Surkhan and Kafirnihan, just as Kubadian at the southern end of the latter stream defended them from the south. The famous bridge of Pul-i-sanghin (stone bridge, Tash-kepri in Turkish) lies on the road from Hissar and Kafirnihan to Baljuan and Kulab. It spans the Surkhab, which is here hemmed in between lofty and precipitous cliffs barely 30 paces apart. The bridge itself abuts on projecting rocks and is ten paces wide. The next place of importance is Kulab, in the valley of the Kichi Surkhab, so called from the lakes or inundations near which it stands. The district is part of that once famous as Khotl. The town (which, strictly speaking, is the capital of Kulab district as distinct

In the

History. Our knowledge of the history of Hissar is most fragmentary. In early written history this country was part of the Persian empire of the Achaemenida, and probably afterwards of the Græco-Bactrian kingdom, and then subject to the Eastern swarms who broke this up. time of the Sassanian kings of Persia it was under the subdued by the Turks in the early part of the 7th century, Haiathalah, the Ephthalites or White Huns of the Greeks, these soon to be displaced by the Mahometan power. Termedh, Kubadian, and Chagámán are named as places of importance by the Arab geographers of the 10th century; the last name was also applied territorially to a great part of the Hissar province, but is now obsolete. The country was successively subject to the Mongol Chagatai dynasty and to Timur and his successors; it afterwards became a cluster of Uzbek states of obscure history. Hissar was annexed by the amir of Bokhara in 1869-70, soon after the Russian occupation of Samarcand.

(C. E. D. B.)

HISTOLOGY.

I. ANIMAL HISTOLOGY.

stricted; and each such set of cells, destined for the

ANIMAL HISTOLOGY (from iorós, a web or tis- performance of a special function, and modified accord

A

B

Ent

Ect

sue, and 2oyos, discourse) is the study of the mi-ingly in structure, is denominated a tissue." nute structure of the tissues of animals. By a tissue is The animal tissues may be classed under the four meant any part of an organism which has undergone heads of Epithelium, Connective Tissue, Muscular Tisspecial changes in structure in adaptation to the per- sue, and Nervous Tissue. Of these four classes of formance of special functions. These special changes tissue the epithelium is the most primitive and least are expressed by the general term "differentiation." altered. In the development of the Metazoa the nuIn the lowest animal organisms, the whole of whose merous embryonic cells which result from the division bodies are composed of the undifferentiated living of the single cell-the ovum-tend in nearly every case substance termed "protoplasm," we find all its func- to arrange themselves as a single layer surrounding a tions shared by every part of the organism. An amoeba, central cavity (unilaminar condition of the blastoderm), for example, it is well known, is capable of finding, (Fig. 2, A). Presently a part of the wall of the hollow seizing, devouring, digesting, and assimilating food, sphere becomes invaginated, so that, instead of a vesihas a special provision for collecting fluid and pumping cle inclosed by but a single layer of cells, a cup (Gasit out of its body, respires by its whole surface, moves trula, Haeckel), is produced (Fig. 2, B), the wall of about apparently where it will, exhibits a sensibility to which is formed by two layers derived from the original tactile impressions, and reacts in all probability to smell single layer, and separated from one another by a narif not to sound and light,-in short, is capable of per- row interval (which is all that remains of the original forming, although with the lowest possible amount of cavity of the vesicle) except at the orifice of the cup, activity, almost every function which animals vastly higher in the scale of organization exhibit. But even in the amoeba we cannot say certainly that there is no differentiation of its protoplasm. For a condensed portion-the nucleus-is set aside to initiate the reproductive function, and it is by means of the external and firmer layer (ectoplasm) that its movements are effected and its relations with the external world maintained, while the internal more fluid protoplasm (endoplasm) is concerned with the digestion of the food. Still there are simple organisms whose protoplasm is probably absolutely undifferentiated. On the other hand, there are other organisms which are also regarded as composed of simple protoplasm, and are constituted by a single cell, which nevertheless show a marked progress in the differentiation of portions of their substance apart altogether from the presence of a nucleus. Such differentiation in unicellular organisms generally takes the form of the production of a shell or "test," FIG. 1.-Flagellum of Noctiluca miliaris (highly magnified). s, transas in the Foraminifera and in Noctiluca, which versely striated substance; b, base of attachment to body of animal. subserves purely passive functions of sustentation FIG. 2.-Sections through the unilaminar (A), bilaminar (B), and trilaminar (C) conditions of the typical blastoderm. Ect., ectoderm; Ent., or defence. It is not certain in such cases whether entoderm; Mes., mesoderm; c, primitive connective tissue. the structure thus produced is formed by the direct conversion of the protoplasm or by an exudation on the surface which subsequently hardens. But portions of the protoplasm may be set aside for the performance of active functions. We see this in its production in the form of locomotory organs, either temporary (pseudopodia) or permanent (cilia). But in neither of these can any actual change in the minute structure of the protoplasm be observed. A differentiation does, however, occur in one remarkable instance the flagellum, namely, of the Noctilucida (Fig. 1), which exhibits as definite a transverse striation as does the cross-striated or voluntary muscular tissue of the higher animals, in which structural peculiarity it is impossible not to infer a relation to its contractile functions; and similarly, in the Vorticellidae, there is a differentiation of the protoplasm of the rapidly contractile stalk.

FIG. 1.

FIG. 2.

C

Mes

where they are continuous (bilaminar condition of the blastoderm). At this part some cells become separated from one or both of these two primary layers, and, extending in and occupying the cleft-like space which separates them, become a third layer of cells which differs from those of the other two in not being arranged into a continuous membrane, and not, therefore, forming an epithelium (trilaminar condition of the blastoderm), (Fig. 2, C). Now, of these three layers, the outer one, or ectoderm, and the inner one, or entoderm, give rise to all the epithelial tissues of the body. The nervous tissues are also derived from the ectoderm; whereas the connective and muscular tissues originate in the mesoderm or middle layer. In most of the Calenterata, however, the mesoderm is not developed at one part only of the embryo as in the higher Metazon. In the hydroid polyps and Meduse it never becomes completely distinct from the ectoderm and ento

1 The characters of the several tissues and their varieties are

best known as they occur in the Vertebrata, and a description of them will be found in the article on ANATOMY.

Whereas in the more highly organized unicellular animals portions of the single cell are thus set aside for the performance of special functions, and modified in structure accordingly, in multicellular animals, on the other hand, we find whole cells and sets of cells set apart and differentiated. It is to such modifications of the cells, with an imperceptible amount of intercellular ceA layer of cells which thus forms a membrane by the union in sets of cells in multicellular organisms, rather than menting substance, would properly fall under the definition of in portions of the protoplasm of a unicellular organism, the term epithelium, which was first applied by Ruysch to the cellular membrane covering the lips, and has ever since been that "histological differentiation" is commonly re-used to designate membranes thus composed of cells alone.

FIG. 11.

face of the epithelium cells, and resembling in their their branching cell-processes (see Fig. 2, C, c). Presappearance long cilia, but not spontaneously vibratile ently, in the production of ordinary connective tissue, (Fig. 9). Moreover, the cells in question, which are fibres of two kinds make their appearance in the intergenerally of an elongated columnar form, commonly cellular substance, and to all appearance independent branch out at their detached end into fine processes, of the cells. Those which appear to become connected with nerve-fibres. of the one kind Cells of this character occur even so low in the Meta- (Fig. 11, A) are zoa as the Medusa, in connection with the nerve- highly elastic and epithelium to be afterwards mentioned. And, indeed, refracting, not eain many cases where cells of this character enter into sily affected by reathe constitution of the sense organs, it is probably gents, stain deepmost consistent with their true nature to regard them ly with magenta, as detached portions of nervous tissue, which also, in run singly, always A every case, is originally of an epithelial nature. branch, and beModifications in the Cell Contents.-Another chief come united with modification which the cells of an epithelial tissue may neighboring fibres undergo consists in the accumulation within the cells so as to form a netof various chemical substances, which may be either work throughout taken in bodily as such, or may be formed in the cell the tissue; those from other substances which are supplied to it by the of the other kind blood. The substances that (Fig. 11, B) are are thus accumulated and excessively fine and formed within the cells of an epithelium are of very various nature, as, for example, the constituents of special secretions (Fig. 10), mucin, pigment, fatty globules, uric acid, etc., etc. These several substances are tolerably constant in an epithelium of the same acid. (Boll.) kind-thus, mucin is a very frequent constituent of columnar epithelium, and in glands which have the same function in different animals, the same substances are found in the epithelium cells of the gland. Exudation from Epithelium Cells-Formation of Cuticular Structures.-In many invertebrates the epithelium which covers the surface of the body, and sometimes also that which lines a part of the alimentary canal, forms an exudation which is generally soft at first, but may afterwards harden into a horny consistency, or may be rendered still harder and at the same time more brittle by impregnation with earthy salts. Any such structure is termed a cuticular formation. It may be composed of a single thin layer, or a number of layers may be superimposed, so that a "shell" of considerable thickness is thus formed. The chitinous or calcareous covering which forms the exoskeleton in many mollusks, arthropods, annelids, and Hydrozoa is of this nature. On the other hand, the firm skeletons of sponges, Actinozoa and Echinodermata are formed by deposition in the connective

tissue.

FIG. 10.-Epithelium cells of
renal organ of mollusk con-
taining crystals of uric

The Connective Tissues.-The connective tissues are characterized by the great development of intercellular substance in comparison with the cells; indeed, in those animals in which connective tissue may first of all be said to appear, there is an entire absence of cellular elements properly belonging to the tissue. This is the case in many of the Colenterata, in which the connective tissue is represented merely by a layer, more or less thick, of hyaline substance, which undoubtedly performs a sustentacular function, in addition to connecting together the epithelial layers of the ectoderm and entoderm.

indistinct, never run singly but always in bundles, and generally with a wavy course; are readily affected by reagents, and, in vertebrates, yield gelatin on boiling. In the various kinds of connective tissue, the relative proportion of these two kinds of fibres to one another and to the cellular elements of the tissue varies. Thus in the so-called elastic tissue of the Vertebrata the elastic fibres greatly preponderate; in tendinous tissue, on the other hand, they are scarcely to be found, and the ground is almost wholly occupied by the white fibres. It may happen that the intercellular substance is so completely occupied by the fibres as to be entirely obscured; but its presence may be always recognized in consequence of the property which it possesses of reducing silver from its salts when exposed to the light. In certain cases the intercellular substance becomes hardened by the deposit within it, either of a substance termed chondrin, which confers upon it the well-known toughness and elasticity of cartilage, or by a deposit of earthy salts imparting to it the firmness of bone. These several changes in the intercellular substance are accompanied by special modifications in the form and relations of the cells (by whose agency they are in all probability effected). In comparatively rare cases the intercellular substance which is found occupying the meshes of the network formed by the branched cells of the developing connective tissue may disappear entirely, and the meshes may be occupied either by blood or by the lymph or plasma of the blood (spleen and lymphatic glands of vertebrates).

It frequently happens that the connective tissue presents the consistence of jelly, and this is generally ascribed to the characters of the intercellular substance. It may, however, be due in many cases to the entanglement of fluid in the meshes of the fibres, and not to a gelatinization of the ground substance. This is shown by the fact that the fluid may be drained from out the meshes by means of filter-paper. And the possibility of the formation of a jelly in this manner is evidenced in the coagulation of lymph, where the apparently solid gelatinous clot is a tangled meshwork of fine filaments inclosing fluid.

The connective tissues of invertebrates are, on the whole, similar to those of the vertebrate; at the same time it must be admitted that there are not unimportant differences in chemical constitution, such as the absence of a substance yielding gelatin, and the absence for the most part of mucin, both of which are characteristic constituents of vertebrate connective tissue. On the other hand, the anatomical characters of the elements, both cells and fibres, are in most cases sufficiently well marked to be recognizable.

The intercellular or ground substance almost invariably takes a prominent part in the formation of connective tissue. It is of a semifluid nature, and often contains in addition to albumen a certain amount of mucin. In most cases the cells of the connective tissue separate themselves from the primary layers before the formation of this ground substance; indeed, the mesoderm is at first chiefly formed of these cells. The stages of development are as follows: The mesodermic cells, which are at first in apposition, become separated from one another by the accumulation of In the sponges the bulk of the animal is made up intercellular substance, but at the same time maintain of a jelly which, when examined under the microscope, a connection with one another throughout the tissue by is found to consist of large branched cells (Fig. 12)