EPIPYXIS. 



[ 298 ] 



EPITHELIUM. 



xxiv. 253 ; Thomas, Jahr. iviss. Hot. iv. 33 ; 

 Pfitzer, ibid. vii. 561, and viii. 17 ; De Bary, 

 JBot.Zeit. 1871; Sachs, Sot. 1874; Henfrey- 

 Masters, Sot. 1878. 



EPIP YX'IS, Ehr. A genus of Flagellate 

 Infusoria, of the family Dinobryina. 



Char. Fixed by a pedicle ; eye-spot 

 absent ; no cilia nor appendages. 



E. utriculus (PL 30. tig. 50). Carapace 

 urceolate ; body filled with yellowish gra- 

 nules ; on Conforms ', length 1-650". 



Probably the young state of Dinobryon 

 sertularia, like which it contains a disk- 

 shaped nucleus. 



BIBL. Ehrenb.J/ttf.l23; Kent,Jn/t.400. 



EPISTY'LIS, Ehr. A genus of Infu- 

 soria, of the family Vorticellina. 



Char. Pedicle rigid, not contractile, 

 simple or branched ; all the bodies of the 

 animals of the same form. 



Claparede and Lachmann refer the species 

 of Opcrndaria to this genus. 



Stein has pointed out the occurrence of 

 the encysting-process in the species of this 

 genus ; and indicates the presence of a lid- 

 like discoidal process, protrusible from the 

 orifice, as in Vorticella, furnished with 

 vibratile cilia ; but this does not occur in 

 all the species admitted by Ehrenberg. The 

 species are numerous, and mostly attached 

 to aquatic animals or algae. Clap. & Lachm. 

 admit 19 species. 



E. anastatica (PI. 30. fig. 51 a, c). Body 

 small, conical, not plicate, anterior margin 

 large and projecting; pedicle dichotom-ms, 

 smooth, or covered with minute or foreign 

 bodies; entire length 1-144 to 1-14"; of 

 single body, 1-288". 



E. grandis. Body large, broadly campa- 

 nulate; pedicle decumbent, slender, smooth, 

 laxly branched, not jointed, forming large 

 tufts ; length of body 1-140 to 1-120". 



E. vegetans (ANTHOPHYSA Miillet'i, Duj.). 



BIBL. Ehrenb. Infus. 279 ; Stein, Inf. ; 

 Claparede and Lachmann, Inf. 107 ; Tatem, 

 Mic. Tr. 1868, 31 ; Kent, Inf. 700. 



EPIT'EA, Fr. See UBEDINEI, PHRAG- 

 MIDIUM, and MELAMPSOKA. 



EPITHE'LIUM. The membranous 

 layer lining the various internal cavities, 

 and covering the internal free surfaces of 

 animal bodies, as the mucous canals and 

 cavities, and their involutions forming the 

 glands and ducts, the serous cavities, the 

 vessels, &c. 



It consists of one or more layers of nu- 

 cleated cells, the form and arrangement of 

 which are very variable. They are either 



round, polygonal, spindle-shaped, cylindri- 

 cal, or conical ; and are united by a small 

 quantity of intercellular substance. They 

 contain a clear or granular nucleus, with 

 one or more nucleoli. In some instances 

 they contain granules of black pigment or 

 melanime. 



Three kinds of epithelium are usually 

 distinguished ; but intermediate forms are 

 also met with. 



Pavement- or tessellated epithelium. 

 This consists of roundish, oval, or polygonal 

 flattened ceils, about 1-2000 to 1-500" in 

 diameter, and containing nuclei with nu- 

 cleoli. It occurs upon the Surface of the 

 serous and synovial membranes ; the mem- 

 brane of the aqueous humour, the choroid, 

 the capsule of the lens, the retina, and the 

 conjunctiva of the ball of the eye ; the ca- 

 vity of the tympanum ; the lower half of 

 the pharynx, the oesophagus, the end<>rar- 

 dium ; some veins ; many glands and ducts, 

 as the racemose, the sudoriparous and ceru- 

 minous glands ; the hepatic ducts ; the 

 vagina and female urethra; the bladder, 

 uterus, pelvis, and tubules of the kidneys; 

 and the air-cells of the lungs. In the ai-lc- 

 ries and many veins the cells are spindle- 

 shaped. 



Cylindrical epithelium. In this form the 

 cells are either cylindrical, conical, or pyra- 

 midal, about 1-1000" in length, and so 

 situated that the axis of the epithelial scales 

 or cells is at right angles to the surface upon 

 which they are placed. Sometimes the sub- 

 jacent cells are of a rounded form. 



Cylinder-epithelium is met with in the 

 mucous membranes, inLieberkiihn's follicles, 

 and the ducts of the gastric as well as those 

 of all other glands opening into the intes- 

 tine ; in the lachrymal and the mammary 

 glands ; the male urethra ; the vas defereus ; 

 the vesiculse seminales, the prostatic ducts, 

 with Cowper's and the uterine glands. 



Ciliated epithelium. In this the form 

 and arrangement of the cells is much the 

 same as in the last; but their free ends 

 are furnished with numerous vibratile cilia 

 (PL 49. fig. 13). 



Ciliated epithelium occurs in the larynx, 

 trachea, and bronchi ; the nares and pha- 

 rynx above the level of the base of the nasal 

 bones, and the cavities opening into them ; 

 the inner surface of the membrana tympani, 

 the Eustachian tube ; the uterus, the Fallo- 

 pian tubes ; the lachrymal sac and nasal 

 duct; the palpebral conjunctiva; and the 

 ependyma. 



