320 SPECIAL HISTOLOGY. 



roundish nuclei of 0*002 — 0'003'". The former, in its inner- 

 most part, is constituted of a layer of parallel fasciculi, with 

 indistinct fibrils and elongated nuclei or fine elastic filaments ; 

 more externally of decussating bundles, with a fine elastic 

 network, occasionally also of a network of bundles of connective 

 tissue of very various thickness, with winding elastic fibres, 

 exactly as in the arachnoid. Not unfrequently, common fat- 

 cells occur, dispersed here and there in the meshes of the 

 connective tissue, although upon the whole very rarely; and 

 also a few scattered cartilage-cells, with tolerably thick, opaque 

 Avails, and a distinct nucleus. The synovial membranes possess 

 neither glands nor papillae, whilst they present large adipose 

 masses {plica adiposte) and vascular processes {plica vasculosce, 

 plica synoviales, ligamenta mucosa, Autor.). The former, at 

 one time erroneously termed "Haversian glands/' are found 

 principally in the hip- and knee-joints, in the form of yellow 

 or yellowish-red, soft processes or folds, and consist simply of 

 large collections of fat- cells in vascular portions of the synovial 

 membrane. The latter are met with in almost every joint, con- 

 stituting, provided that the blood-vessels are filled, red, flattened 

 projections of the synovial membrane, with an indented and 

 plicated margin, and furnished with minute processes. These 

 folds are usually placed close to the junction of the synovial 

 membrane with the cartilage, upon which they lie flat, thus 

 forming, in many cases, a sort of coronal around it; in others 

 they are more isolated, and placed in other parts of the 

 articulation. In their structure, they differ from the rest of the 

 synovial membrane, principally in their great vascularity, con- 

 sisting as thev do of little else than minute arteries and veins, 

 and delicate capillaries forming wavy loops at the edge of the 

 processes, and consequently they are very similar to the choroid 

 plexuses in the ventricles of the brain. Besides the vessels, 

 they present a matrix of, frequently, distinctly fibrous, connective 

 tissue, the usual epithelium of the synovial membrane, occa- 

 sionally solitary or numerous fat-cells, and, more rarely, isolated 

 cartilage-cells. At the edge, they are almost invariably fur- 

 nished with minute, foliated, conical, membranous processes of 

 the most extraordinary forms (often resembling the stems of a 

 cactus), which also frequently contain vessels, but are for the 

 most part constituted merely of an axis of indistinctly fibrous 



