TRACHELIUS. 



[ 776 ] 



TRAGACANTH. 



Synopsis of Genera. 



TRACHE'LIUS, Ehrenb. A genus of 

 Holotrichous Infusoria, fam. Trachelina. 



Char. Mouth situated at the base of the 

 trunk-like prolongation, alimentary canal 

 apparently branched. No row of spherical 

 vesicles or lateral lamina. 



T. ovum (Amphileptus ovum, Duj.), in 

 bog-water. Trachelius lamella (PI. 32.' fig. 

 is a Loxophylkim. (Clap. & Lachm. In: 

 345.) 



TRACHELOCER'CA, Ehr. A genus 

 of Holotrichous Infusoria ?= Lacrymaria. 



T. olorLacrymaria olor. 



T. viridis (PI. 31. fig. 33). Body green ; 

 neck as in the last; freshw. ; length 1-120". 



BIBL. Ehr. Inf. 341 ; Clap. & Lachm. 

 Inf. 295: Kent, Inf. 514. 



TRACHELOM'ONAS, Ehr A genus 

 of Infusoria, family Cryptomonadina. 



Char. Body enclosed in a spherical or 

 ovoid hard and brittle envelope, having a 

 small aperture, from which a long flagelli- 

 form filament projects; eye-spot present. 

 Freshwater. 



T. volvocina (PI. 30. fig. 24 d, empty en- 

 velope). Spherical, green, brownish, or red ; 

 eye-spot red; length 1-865". 



T. nigricans. Ovate-globose, green, black- 

 ish brown or reddish ; eye-spot brownish ; 

 length 1-1730". 



T. cylindrica. Oblong-subcylindrical ; 

 bright green; eye-spot red; length 1-1000". 



Other species. 



The bodies represented in PI. 30. fig. 24 

 (b to #), and which are commonly found in 

 bog-water, probably belong here, with the 

 genera Chcetoglena(a), Chcetotyphla (fig. 26), 

 and Doxococcus (fig. 47). The margins of 

 the red envelope appear as a bright red 

 ring, on account of the greater thickness 



traversed by the light. They are probably 

 spores of Algae. 



BIBL. Ehrenberg, Inf. 47 ; Kent, Inf. 388. 



TRACHELOPHYL'LUM, Clap. &Lach. 

 A genus of Trachelina (Holotrichous In- 

 fusoria). 



Char. Anterior part of the body with a 

 prolonged appendage, which has no circlet 

 of cirri ; body flat, without a lateral marginal 

 lobe. Swims without turning on its axis. 

 Two species ; freshwater. (Clap. & Lachm. 

 Inf. 306.) 



TRACHYL'IA, Fr. A genus of Micro- 

 lichens, parasitic on Pertmarice. 



Char. Thallus granular ; apothecia cu- 

 puliform, sessile, black. Spores blackish, 

 1-septate. Three species, on old posts. 

 (Lindsay, Qu. Mic.Jn. 1869, 146 ; Leighton, 

 Lich. JP/470 



TRACH'YTE. See ROCKS. 



TRADESCAN'TIA, L. A genus of 

 Commelynacese (Monocotyledons), com- 

 monly cultivated in gardens under the name 

 of Spider-worts. These plants are cele- 

 brated for having served as material for 

 some of the most remarkable observations 

 on the physiological processes of vegetables 

 as the ROTATION of the cell-contents, 

 and the multiplication of the cells, so well 

 seen in the hairs of the stamens when young 

 (PI. 47. figs. 8 & 9). The stems, petioles, 

 &c. afford beautiful spiral, annular, and re- 

 ticulated vessels, &c. 



TRAG'ACANTH. A gum derived from 

 various species of Astragalus, not consisting 

 of a formless exudation, but of partly dis- 

 organized collenchymatous tissue which is 

 extruded from the medullary rays. It is 

 often used for fastening opaque objects, as, 

 when dry, its surface is dull, unlike gum- 



