EPI8TILBITE. 



EQUID.S. 



So far M the opinion of the writer of this article U of nay value, it 

 U nther in favour of the system of resting three pUnU for three or 

 four month* annually by lowering the temperature to 80* or there- 

 about*, and diminishing the moisture Yery considerably ; indeed in 

 regard to Catgut**, Cfnocket, Plaint, Blrfia, GroJorun, and some 

 other* with deciduous leaves, there U no doubt that the plan is India- 

 penaable ; and it would probably bo equally advantageous with respect 

 to all the kind* with fleshy item* or pseudo-bulbs ; but how far it 

 may suit caulescent species with the habit of Yanda and Aeriilci can 

 only be ascertained by direct experiment 



KI'ISTIUUTK, a Mini-nil occurring massive with attached 

 crystal*. The primary form is a right rhombic prism. The cleavage 

 parallel to the short diagonal of the prUra. Colour white. Streak 

 white. Fracture uneven. Hardness 4~0 to 4-5. Lustre vitreous. 

 Transparent, translucent Specific gravity 2"20 to 2-25. It is found 

 on Faroe Islands and in Iceland. The analysis of the Iceland mineral 

 by Rose U a* follows : Silica, 53'59 ; alumina, 17'52 ; lime, 7 '56 ; 

 soda. 1-78; water, 14-88. 



EPITHELIUM. As on the external surface of the animal body 

 there is covering over all a delicate layer of cells which is called 

 Epidermis, so over the internal surface of the body there U found a 

 layer of cells which are called Epithelial Cells, or Epithelium. The 

 epidermal and epithelial cells are homologues, and are so many modi- 

 fications of a similar general arrangement 



The functions of the epithelial cells vary according to the surfaces 

 on which they are placed. They differ from the epidermal cells in 

 being generally moist from the positions in which they are placed. The 

 cells of the epithelium performing, as they do, the most remarkable 

 part of the functions of the organs of which they form a part, vary 

 much in form and size. In all cases they are soft, contain a nucleus, 

 and an in shape rounded, polygonal, fusiform, or conical Sometimes 

 they occur in one layer, sometimes in several. In some instances they 

 are supplied with cilia. The following is Ko'Uiker's arrangement of 

 the epithelial cells : 



a. Epithelium in a single Stratum. 



1. With rounded polygonal cells. This, called Pavement Epithelium 

 (l-'i-j. A), presents only a single layer. It exists as an investment of 

 the true serous membranes, of most synovial membranes, of the 

 cerebral ventricles (ependyma), of the membrane of Demours, of the 

 back of the iris, and of the inner surface of the choroid (pigment 

 layer) of the capsule of the lens and of the retina, of the internal 

 ear, of the endocardium of the veins, of many glandular vesicles and 

 canals, and of the interlobular ducts of the liver. 



-. With fusiform superficially united cells. .This in called Fusiform 

 Epithelium, and is found in the arteries and many veins. 



3. With cylindrical cells. This is the Cylindrical Epithelium. (Fig.H.) 

 It is found in the intestinal tubes in Lieberkiihn's glands, in the excre- 

 tory ducts of the gastric glands, as well as of all the other glands which 

 open into the intestine, also of the lacteal and lachrymal and other glands. 



4. With cylindrical or conical ciliated cells. This i* the Ciliated 

 Cylinder Epithelium. (Kg.C.) It i* found on the finest bronchia-, in 

 the nasal cavities, on the inner surface of the membrana tyinpaui, in 

 the EiuUchlan tube, in the uterus, and in the Fallopian tube*. 



8. With rounded ciliated cells. This is simple Ciliated Pavement 

 Epithelium, and occur* in the cerebral cavity of the embryo, 

 i. Epithelium in many Layers. 



1. With cylindrical or rounded cells below, rounded polygon*! 



ore or lev flattened cell* above. Thin in called Laminated Pave- 



: 



and certain synovial membranes. 



i With rounded cells below, more elongated ones in the mi.1,11.-. 

 and ciliated conical ones above. Thw is called Laminated Ciliary 

 KpiUwlinin. It occurs in the larynx, trachea, and larger l....n 



cavity, in the lachrymal sac and duct, and the upper half of 

 1M puaryux. 



In many instances these forms of Epithelium pass into each other, 

 where they are placed upon the same surface. 



The functions performed by the Epithelium are various. In the 

 instances where the cells are supplied with cilia, their object seemi 

 to be to give movement to the fluids secreted upon their surfaces, 

 [CILIA.] Those placed on mucous membranes elaborate the prut 

 mucus which covers these organs. In the case of those cells wliii -li 

 are prolonged into the follicles and tubuli of which glandular struc- 

 ture is essentially composed, they are the real organs of secretion. 

 ION.] They separata from the blood, as the materials of their 

 nutrition, the peculiar products elaborated by the gland of which tin -y 

 form a part, and by their death and decay these products are set free 

 to perform their work in the system. Even the cells in which ], 

 spermatozoa are developed for the fertilisation of the ova are produced 

 upon the surfaces of the tubes or follicles of the spermatic glands. 



iKollikcr, Manual of Human Jliidology, translated by Busk and 

 Huxley ; Carpenter, Principle* of Phwioioyy.) 



Kl'ITHKMIA. [DlATOMACE.E.1 



EPOMia [CHL.KNIUS.] 



EPOMOPHORUS. [CHKIROITERA.] 



EPSOMITE, Native Sulphate of Magnesia. It occurs massive, 

 botryoidal, and reniform, on the surface of other bodies, ami in 

 solution in sea and mineral waters. Colour white. Streak white. 

 Structure fibrous, sometimes earthy. Brittle. T;uU- hitter uu<l 

 saline. Found originally in a spring at Epsoin. It forms a large 

 bed near Arequipa in Peru, and is often in fine crystals and silky 

 fibres. 



EQUID-13, a family of Animals to which the Horse belongs. They 

 have but a single finger or toe terminating each extremity ; an 

 finger or toe is incased in a horny-hoof, or shoe. But though the 

 Eiinidte possess but one well-developed toe, there are on each side of 

 the metacarpus and metatarsus two small rudimentary processes 

 which represent two lateral toes. The following is the form of 

 dentition : 



Incuon, ; canines, -Hi ; molars, Inl = 42. 



b 1 1 i; i; 



Various fabulous species of these animals are recorded in the 

 descriptions and figures of some authors; such as the Bisul 

 Horse with a mane extending the whole length of the anim;ii 

 head to tail, and figured by Jonston as the ..Kthiopisch Pferd ( / 

 Jithiopicut). The Wald-Esel is figured by the same author with a 

 unicorn-like horn in the midst of its forehead. These -may be classed 

 with the figures of monstrous horses collected by Aldrovandus, a 

 horse with a human head and face for example, and another with 

 hands by way of anterior extremities, which as he says, according to 

 Suetonius, belonged to Julius Cscaar, and would suffer no one else 

 to mount him : " Gains Julius Caesar utebatur equo iiiaigni pedibus 

 prope huiuanis, et in modum digitorum ungulis fissis," Ac, This 

 last was probably a case of malformation of the hoof; but the 

 painter has given the animal two human hands, with four fingers 

 and a thumb on each, and nails to match. 



Liurueus, in his laat edition of the ' Systema Naturae' (12th), left 

 the Horse (Eyuut) among his Bcllutc (the sixth order of Mammalia 

 in his arrangement), in company with the genera liippojtotamtu, Sut, 

 and Rhinoccrot. His genus Equta consists of the following sp 

 E. Calalltu, E. Atinut, and K. Zebra, and is thus defined by him : 

 Incisor teeth (deutes primores) six above erecto-parallel, six below 

 more prominent; canines (laniarii) solitary, included, remote on 

 each side. Feet with an undivided hoof. 



Omeliu, in his edition of the 'Systema Natiiras' (13th), added to 

 the above definition, 'Teats two, inguinal,' and divided the genus 

 into two sections 1, species with bisulcated feet ; 2, species with 

 Holidungulous feet The first section consists of one species only, K. 

 bucultu, the 'Equus pedibus bisulcis,' Molin., 'Hist Nat Chil.' 

 This was most probably a Llama. The second section embrace* 

 the following species : Eyunt Caballut, . Jlemiontu, E. Atmn$, 

 B. Zttra, and . Qitagga. 



Cuvier places the Solin&des at the end of his Hammiferous 

 Pachyderms, and makes this family to consist of only one genus, 

 Riunt, with the following species : CabaUut, Jhmionut, Asinut, 

 Zebra, Quagya, and Montana*. 



Dr. Gray, in his ' Revision of the Family Equidce ' (' ZooL Journ.,' 

 vol. i), observes that the older authors speak of th- li 

 Onager, Ass, and Zebra, the last of which they generally describe as 

 having the body (corpus) striped with black, brown, and wbito 

 bauds, three inches broad, but take no notice of the colour of its 

 legs; but in Jonston's figure they are distinctly bandod. After 

 referring to the other figures in Jonston and to Molina's (MMUP-I. >] 

 Huemul, fyuiu buukutpt Qmolin, which, if it exist*, Dr. Gray connidcn 

 to lie probably a species of Llama (Auclicnia), he notices the 1 

 in Edwards'* ' Gleanings' the species recorded by Liunams, Polios, 

 nml linrchcll, the Quagga sent by Captain Gordon from the Caj>o to 

 Amsterdam, where it was first described and figured from his drawing 

 in the Dutch edition of Buflbn, and afterwards in the mpplenieiit of 

 the French editions; and L'Ano Isabellc of Lo ViiilUnt. With 

 regard to the last, which is described as being of a plain Isabella 

 colour without any band, Dr. Gray observes, that uobody since Le 



