94 MANUAL OF HISTOLOGY. 



water before immersion in any staining fluid. In preparing a 

 specimen for cutting with the knife it may conveniently be 

 held in the hand, or, if the microtome is used, the bone may 

 be embedded in the ordinary mixture of wax and oil, pith, or 

 liver, according to methods already described. Rutherford re- 

 commends glycerine jelly for this purpose. 



Any of these plans of preparing decalcified bone will reveal 

 the presence of the bone-corpuscles within the lacunae. These 

 will be found to correspond quite closely in size and shape 

 with the cavities. They may also be shown to have a direct 

 continuity with the connective- tissue corpuscles of the perios- 

 teum. In growing bone this is more evident. A nucleus can 

 also sometimes be seen in the bone-corpuscle. In Fig. 36 

 the lacunae, with their canaliculi, are well shown. 



Sharpens perforating fibres. Attached to the outer sur- 

 face of compact tissue, and penetrating the bone at right an- 

 gles, are certain fibres which have been named after Sharpey, 

 their discoverer. 



Take a flat bone of the skull that has been decalcified, seize 

 pieces with the forceps, tear them out from the surface, and 

 examine in water. In some of the fragments the bundles of 

 fibres will be seen ; in others the lamellae, perforated for the 

 fibres. If a portion of tendon adhere to the bone, and a sec- 

 tion be made through the two at their line of apparent junc- 

 tion, it will be seen that the tendon-fibres are continuous in 

 the bone with Sharpey' s fibres. 



A very prevalent view is that they constitute the remains of 

 the periosteal processes, which we shall see are largely con- 

 cerned with the ultimate development of bone. 



Cancellous tissue. All of the elements of bone, that go to 

 make up a Haversian system, are found in the cancellous 

 tissue, so that, in this respect, it does not differ from the com- 

 pact. The chief peculiarity lies in the marrow cavities, or 

 channels, as they might appropriately be called, and they indi- 

 cate either, on the one hand, that the bone is passing through 

 a developmental stage ; or that it is being rarefied by a process 

 of retrograde metamorphosis ; or, finally, that it has reached a 

 stadium of repose in either of the first-named changes. These 

 points will be further particularized when the growth and de- 

 velopment of bone is explained, but the reader is now prepared 



