XI] ELASTIC CARTILAGE. BONE. TEETH 89 



2. Transverse section of dried parietal bone. Note 

 the surface layer of compact bone and the median layer 

 of spongy bone. 



3. Transverse section of rib to show red marrow 1 . 

 Note the numerous marrow cells, the scattered fat-cells 

 and occasional giant cell. 



4. Transverse sections of teeth through the crusta 

 petrosa and through the crown. Compare with the 

 longitudinal sections described in the text. 



5. Longitudinal section of decalcified tooth, showing 

 the pulp. 



NOTES. 



Intervertebral discs. Remove the spinal cord from (e.g.] a 

 rabbit. Take several successive vertebrae. Saw through them 

 about 3 mm. from the intervertebral disc. Place the discs with 

 the bone attached, in a hardening and decalcifying fluid. 



Hcematoblasts. A film may be fixed in the manner given for 

 blood (p. 28) and then stained with hsDmatoxylin and picric acid 

 or haBinatoxylin and eosin. Or a film may be fixed by osmic 

 acid vapour and allowed to dry. 



To see the hocmatoblasts in the fresh state the marrow is 

 teased in salt solution tinged with methyl-violet ; different 

 strengths of salt solution should be tried. 



Red marrow may be fixed in bone by mercuric chloride, 

 Muller's fluid, or other agent which fixes haemoglobin. The 

 bone is decalcified by picric acid. 



1 Short piece of rib of growing animal, fixed in mercuric chloride ; 

 decalcified ; imbedded ; stained on the slide. 



