298 SPECIAL HISTOLOGY. 



measuring OOOOS'" (fig. 114). If water or weak syrup, or 



albumen, be applied to a slice of bone, it assumes a condition 



Fig. in. probably similar to 



that which it pos- 

 sesses during life. 

 l> The lamellae, for the 

 b most part (both in 

 , transverse and per- 

 pendicular sections), 

 ■• ■*"-■ become clearly visi- 

 ^ ble, and their gra- 



nular aspect is quite distinct, although not sodefined as before the 

 bone was thus treated. For in the first place, together with the 

 granules, there is exhibited a close, pale striation, referable to the 

 canaliculi, which are filled with fluid, and which, extending in 

 various directions through the tissue, renders its delineation more 

 complex; there are also apparent in each lamella, as it were, 

 two layers, one pale and more homogeneous, the other darker 

 and granular, which latter chiefly is striated. When this 

 condition is clearly displayed, an extremely delicate marking 

 is produced, resembling that seen in transverse sections of 

 certain urinary calculi (fig. 113). When once seen in moistened 

 sections, indications of this arrangement will occasionally be 

 observed in dried preparations. In bone treated with hydro- 

 chloric acid, the granules and striae (dependent on the canali- 

 culi), in sections both transverse and perpendicular to the 

 surface, are less distinctly apparent, whilst the lamellar structure 

 is very manifest, and most generally two layers may be noticed 

 in each lamella, though by no means so clearly as shown in 

 fig. 113. 1 In sections parallel to the surface, the bone, in 



Fig. 114. Portion of a perpendicular section of a parietal bone, x 300 diam.: 

 a, lacunae, with pale, only partially-visible prolongations, filled with fluid as in the 

 natural state ; b, granular matrix. The striated places indicate the boundaries of the 

 lamellae;. 



1 [According to Tomes and De Morgan, the laminae, when well developed, are 

 always constituted of two portions, — an outer, highly granular, often composed of a 

 single line of large granules, and an inner, which is singularly clear and transparent, 

 and to all appearance without granulation or any recognisable structure. This distinct 

 separation into two layers, however, does not always exist ; and in a complete Haver- 

 sian canal, the innermost lamina of all is frequently clear, glassy, and structureless. 



The circumferential laminae are not so constantly present as is generally supposed, 



