32 PRACTICAL HISTOLOGY. 



BONE LAMELLAE. 



PREPARATION. (a) With forceps pull off a thin layer of the peripheric lamellae from a 

 bone softened in dilute hydrochloric acid (p. xxxiii) and denuded of its periosteum. Examine 

 in water. If it is to be preserved, it must be placed for twenty-four hours in one-half per 

 cent, osmic acid, and mounted in Farrant's solution. 



(b) Digestion of a piece of bone with artificial pancreatic juice (p. xxxiv), previously softened 

 with dilute chromic acid, enables one to isolate the fibres of which the lamellae are composed. 

 (Birch.) 



The sections must be preserved in a ten per cent, solution of sodic chloride. 



EXAMINATION (H). The thin sheet of tissue consists of fibres resembling white fibrous 

 tissue, which appear to cross each other in two directions, and here and there a hole may be 

 seen, through which a Sharpey's fibre had passed. Projecting from the surface may be seen 

 finger-like processes ; these are Sharpey's fibres, which have been pulled out of their sockets. 



SHARPEY'S FIBRES. 



PREPARATION. Decalcify a piece of a human parietal bone in dilute hydrochloric acid. 

 Make vertical sections, and place one on a slide. With needles tear off the peripheric lamellae, 

 using a dissecting microscope (p. xxxv). Some of the fibres will thus be torn from their 

 sockets, and will project as fine processes from the lamellae. 



EXAMINATION (L and H). Observe the fine elongated nail-like process, and perhaps 

 the socket from which they were removed. 



In the foregoing preparation of a lamella they are seen directed towards the observer. 

 No Sharpey's fibres, such as are described above, are found within the Haversian systems. 

 They are found in the peripheric and intermediary lamellae. 



ELASTIC FIBRES IN BONE. 



In addition to these fibres of white fibrous tissue, elastic fibres also pass into the bone 

 from the periosteum. These are best seen in transverse sections of a decalcified shaft of a 

 long bone, which has been slightly stained with glycerine to which a trace of magenta solution 

 has been added (magenta-glycerine). The magenta stains these fibres of a deep red, while 

 the white fibres are unaffected by the dye. Further, the elastic fibres branch, which the 

 white never do. The magenta-glycerine must be allowed to act slowly, and when the section 

 is sufficiently stained, remove it, and substitute for it Farrant's solution, and cover. 



FOETAL BONE. 



This ought to be softened, preferably with picric acid solution (p. xxxii). Select a long 

 bone of a human foetus or the bones of a newly born kitten. They require a shorter time for 

 decalcification than adult bones. Make transverse sections and preserve them in preservative 

 fluid (p. xl) until required. Stain a section with picrocarmine, and mount it in Farrant's solu- 

 tion and cover. 



