EPIPYXIS. 



[ 298 ] 



EPITHELIUM. 



xxiv. 25.*) ; Thomas, Jahr. wiss. Bat. iv. 33 ; 

 Pfitzer, ibid. vii. 561, and viii. 17; I)e liarv, 

 Bot.Zeit. 1871; Sachs, i^oi?. 1874; Ileafrey- 

 Masters, Bot. 1878. 



EPIP YXTS, Ehr.— A genus of Flagellate 

 Infusoria, of the family Diuobiyina. 



Char. Fixed by a pedicle ; eye-spot 

 absent ; no cilia nor appendages. 



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

 urceolate ; body filled with yellowish gra- 

 nules ; on Conferva; length 1-650". 



Probably the young state of Diiiohrj/on 

 sertidnria, like which it contains a disk- 

 shaped nucleus. 



EiBL. Ehrenb.7///(«.123; Kent,Jn/"M.s.400. 



EPISTY'LIS, Ehr.— A geims 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 Opercularia 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 algte. Clap, it Lachm, 

 admit 10 species. 



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

 small, conical, not plicate, anterior margin 

 large and projecting; pedicle dichotomous, 

 smooth, or covered with minute or foreign 

 bodies ; entire lenii-th 1-14-4 to 1-14" ; of 

 single body, 1-288''. 



E. gra)idis. Body large, broadly campa- 

 nulate; pedicle decumbent, slender, smooth, 

 laxlv branched, not jointed, forming large 

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



E. vegetans (Anthophysa Mi'illeri, Buj.). 



BiBL. Ehrenb. Iiifns. 27!); Stein, /»/. ; 

 Claparede and Lnchmnnn, Inf. 107; Tatem, 

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



EPIT'EA, Fr. See Ukkdinei, Pheag- 

 MiDiuM, and Mf.lampsoha. 



EPITTIE'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 granides 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 polvgonal 

 flattened cells, 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 

 tlie pharynx, the oesophagus, the endocar- 

 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 arte- 

 ries and many veins the cells are spindle- 

 shaped. 



Cylindrical epithelium. In this form the 

 cells are either cyhndrical, conical, or pyra- 

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

 situated that the axis of the epithelial scal(>s 

 or cells is at rigbt 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 o^jening into the intes- 

 tine ; in the lachrymal and the mammary 

 glands ; the male urethra ; the vas deferens ; 

 the vesicidas seminales, the prostatic ducts, 

 with Cowper's and the uterine glands. 



Ciliated epithelium. In this the form 

 and aiTaugement of the cells is much the 

 same as in the List ; but their free ends 

 are furnished with numerous vibratile cilia 

 (PI. 40. fig. 13). 



Ciliated epithehum occurs in the larynx, 

 trachea, and bronclu ; the nares and pha- 

 rynx above the level of the base of the nasal 

 bones, and the cavities opening into them ; 

 the inner surfiice of themenibrana tympani, 

 the Eustachian tube ; the- uterus, the Fallo- 

 pian tubes ; the lachrymal sac and nasal 

 duct; the  palpebral conjunctiva; and the 

 ependyma. 



