IV.J HYAXINE CAETILAGE. 55 



5. Examine the section which has been mounted in 

 osinic acid ; the fat globules are stained a deep 

 brown-black, the cell-substance, the nuclei and 

 the matrix are but slightly stained. 



6. Prepare transverse sections of costal cartilage 

 which has been preserved in picric acid (cp. 

 Lesson 1 F. § 3), the sections may be made as in 

 § 4 or the tissue may be imbedded (cf. Lesson vi. 

 § 1). Stain the sections by placing them in a 

 2 p.p. solution of picrocarmine for 5 to 10 minutes 

 or in a very dilute solution (e.g. '02 p.c.) for a 

 day ; if placed in the strong solution they should 

 be looked at now and then to see that they are 

 not overstained. Wash the sections with water 

 and mount them in glycerine. 



Observe that the cells are arranged in groups 

 (each group having arisen by division from a 

 single cartilage cell), note the outline of the thin 

 layer of newer cartilage (capsule) around each 

 cell, sometimes the whole of the cells in a group 

 may be seen to be also surrounded by a thin 

 layer just marked off from the rest of the matrix. 

 Towards the outside of the cartilage the cells 

 become flattened in a direction parallel with the 

 surface. This specimen should be preserved' for 

 examination later (Lesson v. B. § 7). 



' With a small brush or glass rod spread a fairly fluid solution of 

 Canada balsam over the edges of the cover-slip and the adjoining part 

 of the glass slide ; the balsam will dry in a day or so and the specimen 

 can be moved about without fear of the cover-sUp being displaced. 

 If the glycerine in which the section is mounted does not stretch to 

 the edges of the cover-slip the balsam will run underneath it and 



