BARTRAMIA. 



[ 76 ] BASEMENT MEMBRAME. 



distinguished under the microscope (PI. 36. 

 fig. 9). (See Starch.) Pearl-barley is 

 obtained by a peculiar mode of grinding, by 

 which the outer coat or shell of the grain is 

 removed. 



BARTRAMIA, Hedw.— A genus of Bar- 

 tramioideous Mosses, containing several 

 common species. 



B. Wilsoni, C. Miill. = Glyphocarpa ? 



C6T11UQ Wils. 



BARTRAMIACEiE.— A tribe of Bartra- 

 mioideae (operculate Apocarpous Mosses) 

 containing several genera. British genera : 



I. Conostomum. Calyptra dimidiate. Peri- 

 stome simple ; teeth sixteen, lanceolate, 

 erect when wet or dry, densely and nodosely 

 tuberculated, with a median line, connate in 

 pairs at their apices, and coherent into an 

 oblique closed cone, arising at an equal 

 space below the orifice, at the base. 



II. Bartramia. Calyptra dimidiate. Pe- 

 ristome either absent, simple or double. 

 External, of sixteen lanceolate, smooth, tuber- 

 culate teeth, with a median line or sometimes 



Fig. 52. 



separating in the 

 middle, erect when 

 wetted, incurved 

 when dry, red. In- 

 ternal: a membrane 

 with sixteen folds, 

 produced into six- 

 teen lanceolate, 

 keeled,broad teeth, 

 ultimately split in- 

 to two divergent 

 articulated lobes, 

 with one to three 



cilia interposed or Bartramia marchica. 



none (fig. 52). Magnified fragment ofperistome. 



III. Catascopium. Calyptra hood-shaped, 

 smallish. Peristome simple ; teeth sixteen, 

 lanceolate, very short, truncate-lanceolate, 

 differing in form, unequal, transversely arti- 

 culated, with a median line, whitish, rugulose, 

 rigid and suberect. Capsule inclined on the 

 collum, globose, small, discelioid, shining- 

 brown and ultimately growing black, thick- 

 skinned, almost horny, without an annulus, 

 smooth. 



BARTRAMIOIDEiE.— A family of oper- 

 culated Acrocarpous Mosses, of ca3spitose 

 habit and varjdng size. Leaves very va- 

 ried in form, erect or reflexed, with terete 

 nerves; cells parenchymatous, and, except 

 in certain s])ecies, fm'nished with solitaiy 

 papillae on the transverse walls on both 

 faces, mostly square or more or less hexa- 

 gonal ; lax or looseish, and densely filled with 



chlorophyll, or with a persistent primordial 

 utricle, rarely thickened. Capsule with a 

 long neck, funarioid, pear-shaped or spheri- 

 cal, regular or asymmetrical, straight or va- 

 riously inclined, smooth or grooved, with an 

 operculum mostly hemispherical or conical, 

 rarely beaked. This family is divided into 

 two tribes : 



1. Meesiace^. Areolation of the leaf 

 lax, smooth, often destitute of primordial 

 utricle {Meesia), or lax and densely papil- 

 lose (Paludella). Capsule erect, elongated, 

 with a more or less elongated neck, hence 

 7nore or less pear-shaped, smooth, the neck 

 bearing stomata. 



2. Bartramiace^. Areolation either 

 lax and smooth, lax and papillose, dense and 

 smooth, or dense and papillose. Capsule 

 erect or inclined, horizontal or pendulous, 

 regular or asymmetrical, smooth or grooved, 

 but more or less spherical, devoid of stomata. 



BARYTA.— A knowledge of the crystal- 

 line forms of the salts of baryta is sometimes 

 useful in determining the presence of this 

 substance. 



Butyrate of baryta (PI. 6. fig. 4). When 

 rapidly separating from an aqueous solution, 

 it forms a pearly film upon the surface ; this 

 consists of dense aggregations of very trans- 

 parent crystalline laminse, not perfectly se- 

 parable fi'om each other. When more slowly 

 formed, stellate groups of crystals are pro- 

 duced (PI. 6. fig. 4 a). The individual cry- 

 stals are rarely jjerfect, and some are so thin 

 and transparent thattheu- outlines are scarcely 

 distinguishable. 



Hydrofiuosilicate of baryta (PI. 6. fig. 5). 

 Its production is a test for the presence of 

 baryta. The crystals are scarcely affected by 

 either nitric or muriatic acid. 



Sulphate of baryta (PI. 6. fig. 6). When 

 rapidly formed, consists of crystalline gra- 

 nules {a). When more slowly precipitated 

 from dilute solutions, it consists of very 

 minute stellate foliaceous crystals, somewhat 

 resembling those of the ammonio-phosphate 

 of magnesia (6). See Strontia and Lime. 



BiBL. See Chemistry. 



BASEMENT MEMBRANE, of Animals. 

 — Is a very thin, transparent, elastic and struc- 

 tureless membrane, lying between the cutis 

 and epidermis of the skin, and between the 

 epithelium and submucous tissue of the mu- 

 cous membranes and their prolongations. 

 It is of considerable firmness, and serves to. 

 support the layer or layers of epidermal or 

 epithelial cells. It is not always easily sepa- 

 rable and demonstrable, but is perhaps most 



