EYLAIS. 



[ 256 ] 



FAVELLIDIUM. 



EYLAIS, Latr. — A genus of Arachnida, 

 of the order Acariua, and family Ilydracli- 

 nea. 



Chnr. Palpi longish, foiirtli joint longest, 

 the iifth obtuse, somewhat tumid, spinous ; 

 mandibles uuguieulate ; rostrum very short, 

 mouth round ; body depressed ; two approxi- 

 mate pairs of eyes ; eoxa^ eomparatively mu'- 

 row, the fourth only in eoutact with the third 

 at its base. 



E. exteudens (PI. 2. fig. 28). Skin soft, 

 furrowed, w ith the ramified alimentary eanal 

 visible throuijh its substance. Between the 

 two anterior cox;v {d) is seen the bilobed 

 labium {a), the posterior portion containing 

 the round and ciliated mouth, the anterior 

 portion forming a kind of hood ; pal])i (b) 

 with the three first joints very short ; mandible 

 consisting of a long thick joint, with a thick 

 mobile claw (c). Fig. 28 d, imder s\u-face of 

 body, exhibiting from before backwards : 

 the mouth, with the hood, and the palpi; 

 next two groups of anterior coxa^ ; the vulva 

 and two stigmata ; the four posterior coxa? ; 

 and lastly, the anus in the midille, with a 

 stigma on each side. 



The larvjv are hexapod, reddish, pellucid, 

 with the eyes foiu-, wide apart. 



BiBL. Duges, Ann. des Sc. nat. 2 ser. i. 

 p. 156; Gervais, Wnlcken. ^irachnid. iii. 

 p. 207 ; Koch, Deufschl. Cnistac. 



F. 



FADYENIA, Hook.— A genus of Nephro- 

 diea" (PolvpodaN)us Ferns). Exotic. 



F.ECES,— We shall not dwell upon the 

 nature of the objects contained in the ficces; 

 surtice it to say. that they may consist of, — 

 the elements of the various secretions poured 

 into the intestuial canal ; the products of 

 iurianunation ; undigested remains of aiti- 

 cles of food, or bodies taken with the food 

 or drink ; and entozoa. Some of these re- 

 semble others very closely to the naked eye. 

 The use of chemical reagents should never 

 be omitted in their examination. 



BiBL. See Chemistry, Animal. 



FASCLK. — The fascia^ consist of the same 

 elements as Areolar Tissue, and present 

 all the varieties of lU'raui^ement intermediate 

 between it and Texdox. 



FATTY DEGENERATION. See De- 



G EN ER ATT ox, FaTTY. 



FATTY TISSUE, or Adipose Tissue.— 

 This is formed of colourless cells, with a 

 very delicate, transparent, structureless cell- 



wall, enclosing, in the normal state, globules 

 of yellowish fat (PI. 40. fig. 41). The cells 

 generally occur in groups, surrounded by or 

 imbedded in areolar tissue. They are rounded 

 when isolated, or polygonal when aggregated, 

 and from 1-800 to l-oOO" in diameter; and 

 the fat so fills them, that neither the nucleus 

 which they contain, nor the cell-wall, is visi- 

 ble. The fat may be removed by drying 

 them, and dijjesting with a?tlier, when the 

 cells appear contracted and wrinkled. In 

 emaciated and dropsical subjects, each cell 

 contains a munber of small globules of fat, 

 frequently of a reddish colour (PI. 30. fig. 3), 

 together with serum, and the nucleus is very 

 distinct. Sometimes in these cases the cells 

 are somewhat spindle - shaped or stellate. 

 The fat contained in the cells is ordinarily in 

 a liquid state, but sometimes the margarine 

 separates in the crvstalline form (PI. J. fig. 

 Iba). 



In the mammalia generally the fatty tissue 

 occurs in the same localities, and has the 

 same structure as in man. In fishes, the fatty 

 matter is deposited principally in the liver. 

 In reptiles, it occurs chiefiy in the abdomen; 

 thus in the frog and toad it forms long ap- 

 pendages occupying the sides of the spine. 

 In birds, it exists chiefiy between the peri- 

 toneum and the abdominal muscles, and in 

 some of the bones. In many of the lower 

 annuals it appeai-s to exist in the state of 

 solution onl}'. 



Fatty matter maybe deposited in cells of all 

 kinds, as in fatty degexeratiox. During 

 the development of cells, it exists in solu- 

 tion. The action of solution of potash is 

 often of service iu distino;uishino: slobides of 

 sai'code, which have a high refractive power, 

 and much resemble those of fat from this 

 substance, as it dissolves the former, but not 

 the latter. 



B I B L. Todd and Bowman , Phys. of Man ; 

 KoUiker, Mikroskop. J nat. 1. 



FAVELLA. — A form of the conceptacular 

 fruit of the Florideous Alga", where the 

 spores are collected in spherical masses, si- 

 tuated wholly upon the external surface of 

 the frond, as in Ceramium and Callitham- 

 nion. 



FAVELLIDIUM.— A form of the concep- 

 tacular fruit of the Florideous Algav, when 

 the spores are collected in spherical masses, 

 attached to the wall of the frond or imbedded 

 in its substance, as iu Halymenia and Dii- 

 montia. The term is us\ially extended to 

 similar fruits not perfectly immersed, e. g. 

 those of Gigartina, Gelidiuni, &c., where 



