STEUCTTJEE. 87 



separate for a little way, standing out like the threads of a fringe. 

 Most generally they are straight, as represented in the figure ; but they 

 are not always so, for in some parts they assume a curvilinear direction. 

 Acetic or hydrochloric acid causes these fibres to swell up and become 

 indistinct, like the white fibres of connective tissue ; care must there- 

 fore be taken in their examination that the remains of the decalcifying 

 acid be removed from the tissue, by maceration in water or in solution 

 of an alkaline carbonate. Moreover, the fibro-reticular structure is not 

 equally distinct in all parts where its presence is recognisable ; for in 

 some places it is less decidedly marked, as if the filn-illation were incom- 

 pletely developed. 



In many instances the lamellae are perforated by fibres, or rather 

 bundles of fibres, which pass through them in a perpendicular, or 

 oblique direction, and, as it were, bolt them together. These perforating 

 fibres maybe seen, with the aid of the microscope, in a thin transverse 

 slice of a decalcified cylindrical or cranial bone, on pulling asunder the 

 sections of the lamclla3 (as in fig. 51). In this way some lamellai will 

 generally be observed with fibrous processes attached to them (fig. 51 b) 

 of various lengths, and usually tapering and pointed at their free ex- 

 tremities, but sometimes truncated — probably from having come in the 

 way of the knife. These fibres have obviously been drawn out from 

 the adjacent lamena3, through several of which they must have pene- 

 trated. Sometimes, indeed, indications of perforations may be recog- 

 nised in the part of the section of bone from which the fibres have been 

 pulled out (fig. 51 c). The processes in question are thus, so to speak, 



Fig. 51. 



Fig. 51. ^Magnified View of a Perpendicular Section through the ExternaI/ 

 Table op a Human Parietal Bone, decalcified. 



At a, perforating fibres in their natural situation ; at h, others drawn out by separa- 

 tion of the lamellae ; at c, the holes or sockets out of which they have been drawn (H. 

 iluUer). 



viewed in profile ; but they may fi-equently also be seen on the flat sur- 

 face of detached lamella?, projecting like nails driven perpendicularly 



