BONE. 



[ 113 ] 



BORACIC ACID. 



walls of the cancelli and canals, of genera- 

 tions of stellate connective tissue corpus- 

 cles (Osteoblasts), forming a jiseudo-carti- 

 lage, occurs, which becomes calcified to form 

 the true bone ; the absorption of IJie calci- 

 fied cartihige, and the deposition in its place 

 of the new tissue, continuing until the 

 structure of the bone is perfected. 



But in certain bones, as the flat sknll- 

 bones, the jaw-bones \'c., the bone is formed 

 without the aid of cartihige. Here tlie in- 

 ner surfeces of the periosteum produce the 

 osteoblasts, which ultimately become the 

 bone-corpuscles. 



In certain morbid conditions, as inricliets, 

 the development of the bone is arrested at 

 the state of ossified cartilage ; secondary 

 deposit occurring in the cells of the primary 

 cartilage as in the case of vegetable cells 

 (tig. 74), the spaces left having great 

 resemblance to the lacunae and canaliculi of 

 bone. 



Adventitious bone agrees in general struc- 

 ture with the normal; and is met with iu 

 all stages of development. 



To examine the structure of bone, thin 

 sections are requisite. The method of ma- 

 king these is described under Preparation. 

 By macerating bone in muriatic acid dilu- 

 ted with from 10 to 20 parts of water, or 

 nitro-chroniic acid, the inorganic matter is 

 removed, the cartilage being left. Thin 

 sections of this can then be readily made, 

 and stained with picro-carmine or purpu- 

 rine. 



The canaliculi are not easily seen when 

 sections of bone are immersed in liquids ; 

 for these fill them up. But it is a dirticult 

 matter to measure the lacunre, unless the 

 section be moistened with turpentine or 

 other liquid. 



^'ery thin sections may be preserved in 

 the dry state ; those which are thick may 

 be mounted in inspissated Canada balsam, 

 which does not easily enter the canaliculi, 

 yet greatly increases the general trans- 

 parency of the section. 



BiBL. Kolliker, Mikr. Anat. ii. ; Tomes, 

 Todd's C'l/cl. Anat. and I'/ii/s., art. Osseous 

 Tissue; Quekett, Tr. Mic. Soc. 1846; 

 Quain and Sharpey, Anat. ; H. Midler, 

 Sieb. Si- Kiill. Zeitschr. ix. 147 ; Rutherford, 

 Hist. 82 ; Schonev, Sch. Arch. xii. devel. 

 (M. 31. Jn. xvi."l876, 67, tigs.); Frey, 

 Histoloqie, and the full Bibl. therein. 



BONNEMAISO'NIA, Ag.— A genus of 

 Laurenciaceae (Florideous Algae), bearing 

 pear-shaped spores in stalked ceramidia. 



7, pi. 12 D ; Greville, Al(jce 



B. ftspai'agoides (PI. 4. fig. 15) has a frond 

 4 to 12 inches lonj^-, frrmving near Inw-water 

 mark or deeper, of ddii-ate feathery cluiracter 

 and deep crimson colour. 



Bibl. Harvey, Flii/c. Brit. pi. 51 ; Br. 

 Mar. A/(/<T, p ~ - - . — 

 Br. p. ]()('., pi. 1^ 



BURACIC ACID is the acid of the 

 well-known salt, borax, in which it exists 

 combined with soda, in the pi'oportion of two 

 atoms of the acid to one of tlie base. Buraric 

 acid is prepared by mixing three parts of 

 borax dissolved in tw^elve parts of boiling 

 water with one part of sulphuric acid or 

 common oil of vitriol. As the mixture cools, 

 the boracic acid separates in the crystalline 

 form. It may be purified by re-solution in 

 hot Avater, and subsequent cooling ; finally, 

 the crystals are pressed betw^eeii blotting- 

 paper, and dried. Ijoracic acid belongs to 

 the doubly oblique prismatic system ; and 

 the crystals possess two optic axes. Those 

 deposited from the hot aqueous solution are 

 mostly six-sided plates ; they exhibit the 

 phenomena of analytic crystals, but at their 

 lateral surfaces or edges only ; and when 

 their entire surface appears dark or co- 

 loured with the polarizer alone, the crystals 

 are found to be laminated. But when an 

 alcoholic solution of boracic acid is evapo- 

 rated on a slide, or, still better, when some 

 phosphoric acid is added to a solution of 

 borax, and the mixture evaporated, minute 

 disks or spheiiiles of the acid are formed ; 

 these wdien carefully examined, are seen 

 to be composed of minute needles radiating 

 from a centre, exactly as iu the oxahu'ate 

 of ammonia. In some of them the needles 

 are so closely in contact that they are un- 

 distinguishable and the circumference ot 

 the disk appears entire ; in others, the free 

 extremities of the needles are seen projecting 

 beyond the circumference. They ai-e per- 

 fectly colourless, and almost transparent 

 when viewed by ordinary light, immersed in 

 balsam. But when examined with polarized 

 light, each disk exhibits the most beautiful 

 cross and coloured rings, just as in the case 

 of the oxalurate of ammonia, in which we 

 have described the phenomenon more fully. 



In some of the specimens of boracic acid 

 the crystals form -elegant arborizations, 

 which also possess considerable analytic 

 power. 



The proportions of phosphoric acid and 

 borax requisite to produce the disks cannot 

 be laid down : they can only be prepared by 

 accident in anumber of trials. Even the same 



