THE OSSEOUS SYSTEM. 343 



examined without the addition of fluid, and presents as perfect figures 

 as those represented in Figs. 115-117. The grinding of the bone with 

 oil is not to be recommended, because the lacunae, then become filled 

 with the oil, and even after thorough treatment with ether can seldom 

 be rendered distinct. Next to sections of bone, the investigation of the 

 bone-cartilage is the most worth while. This tissue is prepared by the 

 treating of bone in the cold, with diluted hydrochloric acid (1 part acid, 

 10-20 water), until the fluid, which is to be frequently changed, no 

 longer affords any precipitate with ammonia ; for which purpose, in 

 small fragments of bone, some hours, in entire bones several days, are 

 required. From the cartilage thus obtained, sections are now to be 

 made with a sharp knife in all directions, suitable chiefly for the study 

 of the Haversian canals and lamellae, which may even be raised from 

 the surface. The lacunte, also, are still visible ; their prolongations or 

 canaliculi appear as fine streaks, and their nuclei are seen without fur- 

 ther trouble, especially also after treatment with potassa, or in cartilage 

 which has been half dissolved by boiling in water. After long macera- 

 tion in hydrochloric acid, the lacunae even become isolated, as stellate 

 bodies with delicate walls, or, in the cementum of the horse's tooth, as 

 structures corresponding to the former cartilage-cells. After long 

 softening of bone-cartilage in water, the lamellar systems of the Haver- 

 sian canals become more or less completely separated, presenting the 

 appearance of short, coarse fibres among the larger lamellae (Gagliardi's 

 claviculi). If bone be exposed in a platinum capsule to a strong white 

 heat, the organic parts burn away, the bone becoming at first black, 

 and ultimately perfectly white ; and, if due care be taken, the earthy 

 constituents are left, completely retaining the original figure of the 

 bone. Preparations of this kind are proper for the study of the lami- 

 nated structure of the compact substance and of the lamellar systems 

 of the Haversian canals, which, in this case also, sometimes appear 

 isolated, as in macerated bone. For the microscopic examination of 

 the inorganic constituents of bone, sections are subjected to heat on 

 platinum foil, but they must be very thin, as they afterwards become 

 more opaque, and, on account of their fragility, except in minute frag- 

 ments, do not admit of being ground thinner (Bruns) ; or sections may 

 be boiled in caustic potassa. In either case, the lacunae are seen dis- 

 tinct, and empty, with the beginnings of the canaliculi, in a finely 

 granular matrix. The natural condition of the lacunae is readily seen 

 in perfectly recent bone, in thin sections or laminae ; as, for instance, 

 in many parts of the bones of the face. In recent bone, also, the 

 vessels may be studied, naturally injected, and with the microscope, 

 being thus, far fitter for the purpose than when injections, which often 

 fail, have been practised, and for the closer examination of which, more- 

 over, the bones must afterwards be macerated in hydrochloric acid, and 

 preserved in oil of turpentine. The nerves of the bones may be seen 



