CELL TERRITORIES OF CARTILAGE. 97 



time in chromic acid solution ; those from the latter 

 being mounted and preserved in glycerine as before. 



Preparation 8. The alum process may also be 

 advantageously used. Sections, as thin as possible, 

 of a perfectly fresh rib cartilage are to be mounted 

 in a dilute solution of alum (j per cent.). This will 

 be found to preserve for a time the natural appear- 

 ance of the cells, better almost than any other 

 reagent. 



Preparation 9. Cell Territories of the Matrix. 

 Sections are to be made of a piece of thyroid 

 cartilage that has been preserved in spirit, and are 

 to be stained with logwood. When sufficiently 

 colored, they are transferred to water and then 

 mounted in glycerine. The logwood, besides stain- 

 ing the nuclei of the cells, gives the matrix also a 

 deep purple color. But this coloration of the matrix 

 is not uniform, for some parts become stained much 

 more deeply than others; those regions more imme- 

 diately around the cells and cell-groups, and which 

 therefore are, as commonly considered, the latest 

 formed portions, having apparently more affinity 

 for the coloring matter of logwood than the other 

 and older parts. By this method the whole matrix 

 appears marked out into what may be termed cell- 

 territories^ although series of definite rings can by no 

 means be said to be very apparent around the cell- 

 groups, such as, it is stated, may be produced in 

 sections of cartilage by treating them with a mix- 

 ture of nitric acid and chlorate of potash. 



Preparation 10. Transition to yellow fibro- 

 cartilage, If the arytenoid cartilage of the ox is 

 sliced longitudinally, it exhibits to the naked eye in 

 its lower part the opaline bluish appearance of hya- 

 line cartilage, but in its upper part the faintly yellow 

 aspect of elastic cartilage, the two parts being sepa- 

 rated by a distinct line of demarcation. Take now a 

 thin section from the cut surface, including a little 

 of both parts, and mount, if fresh, in alum solution, 

 or, if the cartilage have been previously hardened in 

 9 



