VEINS. 



[ 674 ] 



VESSELS. 



in addition to the transverse it has longitu- 

 dinal layers. The outer coat is usually the 

 thickest, agreeing in structure with that of 

 the arteries, except that in many veins, 

 especially those of the ahdominal cavity, it 

 contains well-developed longitudinal mus- 

 cular fibres. 



The veins of the brain and some other 

 parts contain no muscular fibres. 



BiBL. Kolliker, MiJcrosJc. Anat. ii. 



VEINS, OF Plants. — The name com- 

 monly applied to the ramifications of the 

 Vascular bundles, forming the ribs of 

 leaves and similar organs. 



VERMICULARIA, Fr.— A genus of 

 Sphseronemei (Coniomycetous Fungi), per- 

 haps stylosporous states of Sphaeriacei, most 

 of the species being included under Sphceria 

 in the British Flora. They grow on decaying 

 stalks, leaves or wood. S. relicina, Dema- 

 tium, culmifraga, trichella and others of the 

 Br. Fl. belong here. Another species, V. 

 atramentaria, is common on decaying potato- 

 stems, forming black velvety patches. This 

 is distinguished from V. Dematium by its 

 straight spores. The erect black hairs of the 

 perithecia are characteristic. 



BiBL. Berk. Brit. Flor. ii. pt. 2. p. 2/4, 

 &c., Ann. Nat. Hist. 2nd ser. v. p. 378; Fries, 

 Summa Veg. p. 419. 



VERMILION, or bisulphuret of mercury, 

 is used as a pigment for injecting. It should 

 be in a finely divided state, in which it is 

 best obtained by levigation ; and should not 

 exhibit any white crystaUine particles when 

 examined as an opake object. 



See Injection (p. 350). 



VERRUCARIA, Pers.— A genus of Ver- 

 rucarise (Angiocarpous Lichens), containing 

 numerous species, having a crustaceous or 

 cartilagineo-membranous thallus growing 

 upon and adherent to bark of trees or stones ; 

 named from the wart-like processes corre- 

 sponding to the perithecia, which open by 

 a pore at the surface. The perithecia have 

 a black rind, enclosing either the whole or 

 the upper half of the nucleus. The spermo- 

 gonia much resemble the perithecia, only 

 they are much smaller; they occur either 

 scattered among the perithecia, or collected 

 towards the margins of the thallus. 



BiBL. Hook. Brit. Flor. ii. pt. 1. p. 152; 

 Leighton, Brit. Angioc. Lich. p. 35; Schserer, 

 Enum. crit. p. 213 ; Tulasne, Ann. des Sc. 

 nat. 3 ser. xvii. p. 215. pi. 3. 



VERRUCARIEiE.— A family of Angio- 

 car])ous or closed-fruited Lichens, charac- 

 terized by rounded apothecia, closed by a 



special perithecium, perforated by a conti- 

 guous pore, and containing a somewhat hya- 

 line, gelatinous, dissolving nucleus. 



Synopsis of British Genera. 



I. Segestrella. Thallus crustaceous, 

 apothecia solitary; excipulum waxy-mem- 

 branous (coloured); ostiole simple, somewhat 

 papillate ; nucleus gelatinous, somewhat 

 hyaline. 



II. Verrucaria. Thallus crustaceous 

 or cartilagineo-membranous, spreading, ad- 

 nate, uniform. Apothecia hemispherical or 

 subglobose, innate and immersed or sessile, 

 excipulum horny, mostly black, with a simple, 

 papillary or perforated ostiole; nucleus gela- 

 tinous, fluid or deliquescent, subhyaline. 



VERTICILLIUM, Nees. Yig. 805. 

 — A genus of Mucedines (Hy- 

 phomycetous Fungi), distin- 

 guished from Botrytis (under 

 which it is included, with 

 Acrostalag'mus,hyYvie%)c\n.Q^Y 

 by the verticillate arrangement 

 of the sporiferous branches. 

 A number of species are de- 

 scribed ; but from the observa- 

 tions of Hoffmann and Bail on 

 the germination of Trichothe- 

 cium, this genus represents 

 only one form of the plants 

 belonging to other genera ; 

 V. ruberrimum, Bonorden 

 {Botrytis verticilloides, Corda, 

 which Hoffmann regards as 

 identical with Aerostat agmus parasitans sand 

 cinnabar inus), having been raised from the 

 spores of Trichothecium roseum, and its 

 "spores" being barren (see Trichothe- 

 cium). Berk, and Broome describe and 

 figure several new species. 



BiBL. Ann. Nat. Hist. ser. 2. vii. p. 101. 

 pi. 7- figs. 15-18; Fries, Summa Veg. (Bo- 

 trytis), p. 491. 



See also Trichothecium. 



VESPA, Linn. — Vespa vulgaris, the wasp, 

 and V. crabro, the hornet, are readily ac- 

 cessible insects for the examination of the 

 sting (Sting). 



VESSELS, OF Plants. — This name was 

 applied by the earlier observers to various 

 elongated tubular structures of vegetable 

 tissues, from a mistaken idea that they cor- 

 responded with the vessels of animals ; and 

 the name is still retained. The spiral, an- 

 nular, &c. vessels are described under 

 Spiral Structures. The term vessel is 

 now geneially contrasted with duct, to 



VerticlUium 

 cyiin drosp orum . 



Magnified 200 

 diameters . 



