284 THE SOLIDS. 



the cells of the cartilages which cover the articulating surfaces 

 of the larger bones. On the free surface the cells are as in 

 most cartilages small, flattened, and disposed horizontally ; 

 the deeper seated cells become larger and longer ; their axes, 

 on the contrary, being directed either vertically or obliquely 

 to the surface ; sometimes also the cells although separated 

 by distinct intervals, are arranged the one above the other 

 in such a manner as that the superior appears to be a con- 

 tinuation of the inferior ; at others an inferior cell appears 

 to divide into two others, placed above it, and thus represents 

 a bifurcation. Henle also states, that he has seen not unfre- 

 quently the outline of a cavity prolonged from one longi- 

 tudinal series of cells to a neighbouring series. It is very 

 possible, Henle goes on to observe, that these cavities form 

 part of a system of elongated canals, which taking an undu- 

 lous course, and sometimes bifurcating, traverse the cartilage 

 from its inferior to its superior surface, and which, when one 

 makes a section, are divided into two portions, the one re- 

 maining in one segment, the other in the other segment. 

 This structure, he proceeds to remark, explains sufficiently 

 why articular cartilages exhibit a fibrous fracture, and why 

 the earlier observers believed them to be composed of fibres 

 which ran perpendicularly to the thickness. 



This ingenious notion of Henle, although it serves to ac- 

 count for some hitherto unexplained phenomena connected 

 with the articular cartilages, is yet of very doubtful application 

 even to them, and certainly no such arrangement of the cells 

 and cavities as that just described belongs to the majority of 

 true cartilages, or to any of the fibro-cartilages. 



Near the surface the articular cartilages are more lami- 

 nated, and may be separated into thin lamellae. 



In the smaller articular cartilages the number of cavities 

 and cells is more considerable, and the superficial layer of 

 cells is not so well marked : the periphral cells are small 

 indeed, but for the most part rounded ; a few are found in 

 the neighbourhood of the bone of an elliptical figure, but the 

 middle layer presents circular cavities, with cells which are 

 either single or multiple. 



