BANANA. 



[ 74 ] 



BARK. 



less it is, the better. It should be kept in a 

 wide-mouthed bottle, covered by a large 

 cap, fitted by grinding. A piece of iron- 

 wire should be kept in the bottle, so that 

 the desired quantity can be at once removed. 

 It becomes thicker by keeping, but may be 

 rendered thinner by mixture with oil of tur- 

 pentine and digestion at a gentle heat. If 

 too thin, it should be exposed to a gentle 

 heat in a bottle covered with paper to 

 exclude dust. 



See Preservation. 



BANANA. See Musa. 



BANGIA,Lyngb. — A genus of Porphyreae 

 (Florideous Algse), placed among the Ulveae 

 by most authors, but stated by ISl. Thuret to 

 be Florideous. They are marine, and form 

 pui'jjlish, brownish-green or red tufts of fila- 

 ments, upon rocks and stones or on the 

 fronds of other Algse, from 1 to 4 inches 

 long, or in B. ciliaris, only " half a line 

 long." Mr. Harvey admits five species, 

 three of them, however, as doubtful : 



1. B. fusco-purpurea, Dillw. Brownish- 

 green or purple glossy, several inches long ; 

 near highwater mark. Phycol. Brit. t. 96 ; 

 Brit. AlgcB, t. 25 C ; English Botany, t. 2055 

 and 2085. 



2. B. ciliaris, Carm. Forming a minute 

 pink fringe on Zostera marina. 



3. Bl. ceramicola, Lyngbye. Purplish- 

 rose. On small Algae ; about I" long. 



4. Bl. carnea, Dillw. Pale red tufts on 

 Confervae. 



5. Bl. elegans, Chauv. Minute tufts 1'" 

 or 2'" long, rose-red, parasitical on small 

 Algae, rare. Harv. Pliyc. Brit. t. 246, 



See ScHizoGONiUM. 



BiBL. Harvey, British Marine Algce, 2nd 

 ed. 1849. 



BARBULA, Hedw.— A genus of Pottia- 

 ceous Mosses synonymous with Tortula, 

 which is indeed the prior name, but was 

 altered on account of its synonymy with a 

 genus of flowering plants (since abolished). 



1. Barhula rigida, Schultz = Tortula 

 enervis, Hook, and Grev. 



2. B. ambigua, Br. and Sch. = T. rigida, 

 Hedw. 



3. B. aloides, Br. and Sch. = T. rigida, 

 Hook, and Tayl. 



4. B. brevirostris, Hook, and Tavl. = T. 

 brevirostris. Hook, and Tayl. (ed. 2). 



5. B. papulosa, Wilson (Tortula). 



6. B. tortuosa, Web. and Mohr (Tortula). 



7. B. squamosa, Brid. (Tortula). 



8. B. Hornschurchiana, Schultz=:T. revo- 

 luta, Brid. var. 



9. B. unguiculata, Hedw. (Tortula). 



10. B. convoluta, Hedw. (Tortula). 



11. B.fallax, Hedw. (Tortula). 



12. B. revoluta, ^chw.= Tortula revoluta, 

 Hook, and Tayl. 



13. B. subulata, Hedw. (Tortula). 



14. B. muralis, Hedw. (Tortula). 



15. B, cuneifolia, Hook, and Tayl. (Tor- 

 tula). 



16. B. Icevipila, Schw.=T. ruralis, var. 

 Icevipila, Hook. 



17. B. ruralis, Hedw. (Tortula). 

 BARK. — The outer coat of the trunks 



and branches of Dicotyledonous shrubs and 

 trees, succeeding to the epidermis as the 

 young shoots become solid and woody. Bark 

 is a complicated structure, composed of ele- 

 mentaiy tissues of various characters, and 

 the great difi^erences of appearance which it 

 presents upon trees which have attained a 

 certain age, result from the growth and mul- 

 tiplication of the elementary organs being 

 subject to very difi'erent laws in different 

 plants. Bark is the collective term applied 

 to the entire cortical mass outside the 

 cambium region of the stem (see Cambium). 

 It contains three distinct regions or forms of 

 structure, and in young branches, the epi- 

 dermis still remaining on the outside consti- 

 tutes a fourth. 



If we examine a young shoot of the Maple 

 (Acer campestre) while still green, by making 

 transverse and perpendicular radial sections, 

 we find the surface to be covered by an epi- 

 dermis composed of small cells, closely con- 

 joined at their sides. Under this occur six 

 or eight strata of thin-w^alled, colourless 

 cells, which stand vertically over one another, 

 and when mature are elongated in the radial 

 direction of the branch. These form the 

 cork-substance, suberous layer, or ])hl(£um. 

 Beneath or within these, we find a layer 

 composed of parenchymatous cells, filled with 

 chlorophyll granules, forming the cellular 

 envelope or parenchymatous layer; this is 

 continuous within with the external part of 

 the medullary rays. Interposed between 

 the cellular envelope and the Cambium region 

 occur the liber-bundles (see Liber), forming 

 the fibrous layer of the bark. In the bark 

 of the Maple the corky substance grows veiy 

 fast at fii'st, and soon splits the epidermis 

 above it, but after a certain number of years 

 its growth slackens, so that it seldom acquires 

 very great thickness, especially as it is very 

 soft and readily rubbed off"; the cellular 

 layer does not grow fast, merely keeping 

 pace with the enlargement of the stem 



