1^4 PRACTICAL HISTOLOGY. [XIII. 



ADDITIONAL EXERCISE. 



13. Mucous Tissue. Many branched cells are seen in a T.S. of the tail of a 

 tadpole, young triton, or salamander, hardened in I per cent, osmic acid and 

 cut in paraffin. 



It is also to be found under the skin of the flanks in frogs at the breeding 

 season. It gives good preparations when stained with methyl-violet-5B 

 (S. Mayer). 



LESSON XIII. 

 BONE, OSSEOUS TISSUE, &c. 



THE essential elements of osseous tissue, of which bone consists, 

 are a calcined fibrous matrix or ground-substance, with cells or 

 bone-corpuscles embedded in it; the latter are lodged in spaces 

 called lacunw. A bone, however, is a complex organ. The follow- 

 ing scheme may facilitate the comprehension of its minute 

 structure : 



BONE. 



In a longitudinal section of a long bone, observe with the naked 

 eye 



Periosteum covering the bone. 



Compact or dense bone, the substantia dura (with Haversian 



canals). 

 Cancellated or spongy bone, the substantia spongiosa (with 



Haversian spaces and cancelli). 

 Medullary cavity with marrow. 



Histologically dry compact bone shows 

 [Peripherie or circumferential. 

 2| | Haversian or concentric. 

 ce 'i Intermediary, interstitial or ground. 

 [Perimedullary, 



^ ( white. 

 Sharpey s perforating fibres j yellow> 



HAVERSIAN SYSTEM. 

 Dry bone. Recent bone. 



( Blood-vessels, connective tissue, 

 Haversian canal . . . . lymphatics, osteoblasts. 



i Between the lamellae, branched 

 Iaraell8e ' ' ' bone-corpuscles. 



Lacunae 

 Canaliculi 



j Processes of bone-corpuscles 

 | and lymph. 

 Lymph. 



