82 PRACTICAL HISTOLOGY [XI 



A thin layer of spongy bone, the spaces containing red marrow 

 with a considerable number of fat-cells. 



A little farther from the disc, a layer of cartilage, with cells 

 iu rows as if ossifying ; and a little farther still, spongy bone 

 with red marrow and fat-cells. 



3. Elastic Cartilage and transition to Hyaline 

 Cartilage. Vertical sections of apex of (e.g.) sheep's 

 arytenoid cartilage 1 (picric acid). 



a. Stain a section with dilute hsematoxylin (half- 

 an-hour), wash with tap water, place in '5 p.c. solution 

 of acid magenta in 75 p.c. alcohol for a few seconds, 

 and then in water or dilute alcohol till the deep red 

 tint of the section is lessened. Dehydrate and put in 

 clove oil. 



b. Stain another section in the following way : put 

 it in a small quantity of orcein solution (cp. p. 311) in a 

 watch-glass, place the watch-glass on the warm bath 

 till the solution has nearly evaporated, wash the section 

 with water, put it in acid alcohol for a minute or two 

 till the connective tissue at the edge is nearly de- 

 colourized ; dehydrate and put in clove oil. 



Mount the two sections together in balsam and 

 observe (h. p.) 



The hyaline cartilage, showing at its upper 

 border, fine granular fibres the elastic fibres in the 

 matrix. These rapidly increase, till the matrix consists 



1 The apex of the arytenoid cartilage is cut off and the mucous 

 membrane removed ; the two small elastic cartilages at the top 

 (cornicula laryngis) may be left unless they make the section too 

 long. The epiglottis may be taken instead of the arytenoid, but 

 it does not contain hyaline cartilage. 



