CALCIFICATION. 55 



The globular, or rather discoidalj masses arc tlie calcified 

 fibrilla) seen in transverse section. There is nothing strange, 

 therefore, in our meeting with this spheroidal segmentation of 

 the calcified matrix in fibro-cartilaginons structures; and we 

 have already seen, when considering the phenomena of softening, 

 that the matrix of hyaline cartilage is also liable, under certain 

 conditions, to break up into fibrilloB. 



The calcification of cartilage, when the cells arc primarily 

 affected, gives rise to optical results of a very diflferent order. 

 In this case a peculiar thickening of the cartilage capsules 

 (sclerosis, Virclioio) precedes all further changes. The thickened 

 capsule takes up the earthy salts ; sometimes, and indeed usually, 

 as a cloud of earthy granules ; occasionally, however (as was 

 first observed by Kblliker in rickets), the calcareous impregna- 

 tion gradually leads only to a whitish opalescence by reflected 

 light, while the structure never loses its trcmsparency. It is 

 this latter circumstance which has enabled us to ascertain that 

 the entire series of these changes takes place without involving 

 the proper substance of the cells. From first to last the process 

 is exclusively capsular. The capsule continues to grow thicker 

 at the expense of its cavity. The size of the original cartilage 

 cavity, therefore, undergoes progressive contraction, the capsule 

 loses its spheroidal form ; for, as the thickening of the capsule 

 does not proceed uniformly at all points, little funnel-shaped 

 gaps being left at regular intervals (analogous to the pores of 

 vegetable cells during their conversion into wood), the cell-con- 

 taining cavity ultimately assumes a stellate, jagged outline, 

 singularly like that of a lacuna of bone. Should the matrix 

 attain the glassy and transparent stage of its calcification, either 

 simultaneously or subsequently, wx may fairly speak of a direct 

 ossification of hyaline cartilage. Such false hone, Avhich stands 

 towards true bone in the same relation (§ 52) as other calcified 

 connective tissues, such as tendons, fasci[,e, coats of vessels, &c., 

 is not common ; it always occurs in small bits ; we find such 

 bits in enchondromata, and in the spongy substance of ricketty 



to the contact of adjacent circles; for we sec them varying in size 

 and shape within the widest possihlc extremes. {See the annexed 

 drawing of a transverse section through an ossified pleuritic false mem^ 

 branc;) 



