THE MUSCULAR SYSTEM. 257 



thick walls, and dark contours ; the mother cells measuring as 

 much as 0*02 — (VOS"'; and lastly, elongated cells with concentric 

 deposits; inclosing a nucleus, or nucleated secondary cell. In the 

 tendons, the simpler forms of cells almost exclusively occur, 

 and the cells, although frequently extremely numerous, are for 

 the most part isolated, or, at most, disposed, in rows or groups 

 of 2 — 6, which are contained in the connective tissue, both 

 superficially and more deeply. In most cases the common 

 connective tissue alternates with one more resembling fibro- 

 cartilage, so that the tendon, on a transverse section, presents a 

 speckled, white and yellowish aspect ; or it may be, that the 

 outer surface only of the tendon contains cartilage, the deeper 

 portions retaining their usual condition. Where the depo- 

 sition of the cartilage cells is most abundant, the tendons become 

 thickened, or even studded, as it were, with distinct, fibro-car- 

 tilaginous masses (peroneus longus, tib. posticus). In the 

 mucous bursas and. the other parts above named, the cartilage 

 cells are placed, not unfiequently, 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 \ — |'" 

 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 

 bursa?, since they have, invariably, an epithelial lining in cer- 

 tain places; they bear just as little resemblance, however, to 

 the proper serous sacs (pleura, peritonaeum, &c), because, with few 

 exceptions, their epithelium is never complete, and also because 

 the cellular coat of the serous membrane is, almost universally, 

 wanting entirely in some spots. The synovial sacs of the 

 muscular system, on the other hand, and the synovial capsules, 

 which also never possess a complete epithelium, and frequently 

 communicate with mucous bursse, (quadriceps femoris,popliteus, 

 subscapularis, &c.) belong to one and the same category, and 

 differ in some points from the serous sacs; with respect to 



i. 17 



