UVELLA. 



[ 668 ] VASCULAR BUNDLES. 



enlarged and more numerous, from new- 

 formation (fig. 795). 



All three of the coats of the veins of the 

 pregnant uterus contain muscular fibres. 

 After parturition, many of the muscular 



Fig. 795. 



Muscular elements from a uterus at five months' preg- 

 nancy, a, formative cells; b, young, c, fully developed 

 muscular fibres. Magnified 350 diameters. 



fibres undergo fatty degeneration, and be- 

 come absorbed (fig. 794). 



BIBL. Kolliker, Mikr. Anat. ii. 



UVELLA, Bory, Ehr. A genus of Infu- 

 soria (Algae ?), of the family Monadina. 



Char. Corpuscles tailless, without an eye- 

 spot, moving by means of one or two flagel- 

 liform filaments, or an anterior circle of cilia, 

 and aggregated into spherical revolving 

 clusters. 



U. virescens (PI. 25. fig. 18). Corpuscles 

 ovate, rounded at each end, bright green. 

 Aquatic ; diameter of clusters 1 -288", length 

 of corpuscles 1-2016". 



Five other species, one green, the rest 

 colourless. 



Dujardin regards the presence of the fla- 

 gelliform filament as a character of the genus. 



BIBL. Ehrenberg, In/us. 19; Dujardin, 

 Infos. 300. 





V. 



VAGINICOLA, Lamarck, Ehr. A genus 

 of Infusoria, of the family Ophrydina. 



Char. Solitary ; body ovoid or campanu- 

 late, sessile, in a membranous, urceolate,' 

 sessile sheath. 



Cilia forming an anterior circle. 



V. crystallina (PI. 25. fig. 19). Sheath 

 crystalline, urceolate, straight, internal gra- 

 nules green. Aquatic; length 1-216". 



Stein has observed the Acineta-form (Aci- 

 neta mystacina] of this animal, and the sub- 

 sequent development of swarm-germs within 

 it. 



Several other species. 



BIBL. Ehrenberg, In/us. 295 ; Dujardin, 

 Infus. 560 ; Stein, Infusoria, passim. 



VALLISNERIA, Mich. An aquatic ge- 

 nus of Angiospermous Flowering Plants, 

 belonging to the family Hydrocharidacese. 

 V. spiralis, a native of the South of Europe, 

 occurring wild also in North America, India, 

 &c., is commonly grown in jars for the sake 

 of observing the ROTATION in the leaves. 

 This plant is dioecious, and the specimens 

 ordinarily found in cultivation are the pistil- 

 late forms, which often produce flowers, but 

 the seeds, remaining unfertilized, never ripen; 

 the plant increases rapidly, however, by run- 

 ners, if in a healthy condition. We find it 

 thrive well in any situation indoors near a 

 window and not exposed to frost, but it 

 attains far larger size in water kept at a high 

 temperature, as in Victoria-tanks in Botanic 

 Gardens. It is necessary, when growing it 

 in jars, not to keep too many or too large 

 " snails " in the water, as they destroy the 

 leaves. See ROTATION. 



VARIOLARIA, Pers. A spurious genus 

 of Lichens, founded upon imperfect forms 

 of PERTUSARIA, &c. 



BIBL. Hook. Brit. Flor. ii. pt. 1. p. 172; 

 Schaerer, Enum. Grit. p. 229. 



VASCULAR BUNDLES. This title is 

 applied to the fibrous cords which form the 

 ribs, veins, &c., of the leaves, petioles and 

 other appendicular organs of all plants rank- 

 ing above the Mosses, and which by their 

 confluence and more considerable develop- 

 ment constitute the wood of stems and 

 trunks. The vascular bundles of petioles 

 (fig. 665, page 592), &c., running into leaves 

 to form their ribs, and lying imbedded in 

 parenchyma, resemble the bundles which 

 form the rudiments of wood of the stem 

 itself. The bundles remain isolated as fibrous 

 cords in the stems of the herbaceous Monoco- 



