212 SPECIAL HISTOLOGY. 



frequently, in closer aggregation, or in longer rows of 5-10 cells or 

 more, in which rows the terminal cells are invariably the smallest, and 

 the middle ones the largest. On the cuboid bone, where the tendon of 

 the peroneus longus passes over it, there is a layer of true cartilage 

 -^— I a line thick. 



The vascular processes of the tendinous sheaths and mucous bursse, 

 correspond with those of the articulations, only that they are for the 

 most part of smaller size. 



The synovial sacs of the muscular system are not mere meshes of 

 connective tissue, like the subcutaneous mucous burs£e, since they have, 

 invariably, an epithelial lining in certain places ; they bear just as little 

 resemblance, however, to the proper serous sacs [2jleura,peritonceum, &c.), 

 because, with a few exceptions, their epithelium is never complete, and 

 also because the cellular coat of the serous membrane is almost uni- 

 versally wanting entirely in some spots. The synovial sacs of the mus- 

 cular system, on the other hand, and the synovial capsules, which also 

 never possess a complete epithelium, and frequently communicate with 

 mucous bursas {quadriceps femoris, pop)liteus, subscajndaris, &c.), belong 

 to one and the same category, and differ in some points from the serous 

 sacs ; with respect to which, however, it must not be forgotten that transi- 

 tionary forms between these two kinds of sacs exist. 



No one seems to have remarked upon the occurrence of cartilage cells 

 in the various textures which go to the construction of the synovial sacs 

 of the muscular system (except in the fibro-cartilages of the tendons); 

 and the more so, because even Henle refers the fibro-cartilage of the 

 tendinous sheaths to his interarticular cartilages (bandscheiben). It is 

 quite true that the cartilage cells, while often occurring isolated in the 

 connective tissue, or more frequently only in certain spots aggregated 

 together, are not always readily seen ; they may, however, be recognized 

 in sufficiently thin sections, and very distinctly on the addition of acetic 

 acid. The cell-membranes are not in this case utterly destroyed, any 

 more than they are in the cartilage cells of the interarticular 

 ligaments, &c., and no doubt can be entertained as to their being 

 true cartilage cells, which, almost without exception, exist, not as a 

 tissue, but rather dispersed in the connective tissue. Those spots 

 in which they exist in great quantity may be described as fibro-car- 

 tilaginous places; but the distinction between these fibro-cartilages 

 and those of true fibres not of the nature of cellular tissue (epiglottis, 

 ossifying bones), must not be lost sight of. Genuine cartilage, as on 

 the cuboid bone, I have never as yet met with in any other tendinous 

 sheath; not even in the sulcus malleoli externi et interni ; in the sulcus 

 of the heel ; nor in the sheath of the peronceus on the longus calcaneum ; 

 in which situations, cartilage cells are, indeed, everywhere to be seen, 

 but only scattered in the connective tissue. 



