ACCIDENTAL DEVELOPMENT OF CARTILAGES. 39 



fed upon madder, is said by Beclard, to be owing to the small 

 quantity of phosphate of lime which they contain, and with 

 which this coloring matter only has affinity. They participate 

 too in the ulcerative process in many parts of the body, as in 

 those of the nose, and as I have many times seen, in those of 

 the larynx and trachea. 



— All cartilages are divided into two classes, temporary or 

 ossescent, and permanent, a distinction which though not per- 

 fectly exact, is nevertheless very convenient for the purposes 

 of study. The temporary cartilages, (cartilag. temporaricc) 

 are those employed in the development of the bones, those of 

 which the models of the bones are all formed in the foetus, and 

 which gradually as the infant advances in growth give place to 

 bony matter. The substitution of bony matter for the cartilagi- 

 nous, is completed about the period of puberty. 

 — The permanent cartilages (cartilag. pcrmancntes) are devel- 

 oped at an early period of life like the former, but have little 

 tendency to undergo ossification, and retain their cartilaginous 

 character for the whole or the greatest part of life. -These com- 

 prise, the articular and costal cartilages, those of the larynx, 

 eustachian tube, auditory meatus, etc. Some of these have a 

 stronger tendency than the rest to ossify, as those of the larynx 

 and ribs, which are frequently found after the fortieth year of 

 life, converted into bone. 



Accidental develop7nent of Cartilages. 



— In almost every one of the different tissues of the body, car- 

 tilages have been occasionally met with, but in general only after 

 the middle period of life, when from their having apparently 

 no fixed laws of development, they have been called acci- 

 dental. 



— 1st. They are found in the form of plates of greater or less 

 size, adherent by both surfaces to the membranes between 

 which they are formed ; in the arteries, where these plates are 

 most frequently met with, they are attached on their inner 

 surface to the serous lining membrane, and on their outer to the 

 middle coat of the vessel. 



