128 ELEMENTARY BIOLOGY. [CHAP. 



4. Hyaline cartilage. 



Dissect out the xiphisternal cartilage of a recently- 

 killed frog and remove its membranous investment 

 (perichondrium) ; mount in salt solution and examine 

 under a high power. 



a. The matrix ; dense, structureless or finely granu- 

 lated. 



b. The cartilage corpuscles; large cells occurring singly, 

 or in sets of two's to four's, their apposed faces 

 being flattened. Examine the individual cells. 



u.. Cell-protoplasm; finely granulated and usually 

 containing one or many minute refractive par- 

 ticles {fat drops). 



/}. Nucleus ; round and sharply defined, containing 

 a variable number of nucleoli. Two nuclei may 

 not unfrequently be present. 



y. If the preparation be made and examined soon 

 after death each cell will completely fill the 

 cavity of the matrix in which it lies : but if it be 

 kept some time or be treated with distilled water 

 the cells contract; thereupon the cavities (cell 

 spaces) become obvious as transparent halos 

 around the individual cells, or groups of cells if 

 recently formed. 



c. Cell division. The initial phases in this process 

 can be nowhere more favourably made out than 

 here. The undermentioned may generally be 

 found on carefully searching the field ; note that 

 in alU division of the nucleus precedes that of the 

 cell. 



a. Single cells (those filling an entire cell space); 



