PICRIC ACID METHOD. 105 



dissolving the lime salts. In all other respects the 

 proceeding is much the same as for the chromic acid 

 method, except that the pieces will require much 

 longer washing in water, and that the spirit in which 

 they are placed be changed several times before the 

 excess of picric acid can be got rid of. The sections 

 may be stained with logwood and mounted in glyce- 

 rine in a similar manner, and will show the structure 

 as well, if not better, than those prepared with 

 chromic acid. 



Preparation 6. Lamellae and Sharpey's per- 

 forating fibres. For showing these structures, ma- 

 cerated bones that have been decalcified by hydro- 

 chloric acid serve very well. They should before 

 use soak in water for some time, and subsequently 

 lie in spirit, so as to get rid of the last traces of the 

 acid. The point of one of the blades of a sharp pair 

 of forceps is then inserted obliquely into the bone at 

 its outer surface, and a small piece is gripped by the 

 other blade and dragged off in such a manner that it 

 pulls away with it a very thin strip from the super- 

 ficies of the bone. A few such strips having been 

 obtained, either from different parts of the bone or 

 from the same place (at different depths, therefore), 

 they are placed in water on a slide with the inner 

 surface uppermost and examined with a low power. 

 In some places tapering fibres will be seen projecting 

 from the surface of the torn-off strip like nails pro- 

 jecting from a board ; in other parts, round or ovalish 

 holes, corresponding generally in size with these 

 fibres, will be apparent; these are apertures in the 

 lamellae where the latter have been pierced by the 

 fibres of Sharpey, but those fibres have been pulled 

 out in tearing off the strips. Further, there may be 

 made out a faint appearance of decussation in the 

 lamellae, like the checks on a plaid, but oblique in 

 direction, best marked near the thin edge of the strip 

 of bone. These appearances are all more evident 

 when the preparation is covered and examined with 

 a higher power. To preserve the preparation it is not 



