STRUCTURE OF THE SYNOVIAL MEMBRANES. 557 



not the case, one might be easily induced to consider Hitter's 

 view incorrect (Landzert), and to regard the synovial mem- 

 branes as simple serous membranes. But the more the subject 

 is investigated, the more do we become convinced that the sup- 

 position of the superficial irregular (keratoid) markings being 

 imperfectly brought-out endothelial markings is inadmissible. 

 It may be shown that the markings resembling an endothelium 

 occur indeed over the greater part of the synovial membrane, 

 but that there are nevertheless tracts where they never occur, 

 and in regard to these tracts Hiiter's description is undoubtedly 

 perfectly accurate. We may also state in general terms where 

 these tracts are situated. If the highest point of the head of 

 a bone be taken, as, for example, that of the humerus, spheroidal 

 cartilage cells are found around the pole, which in adults are 

 separated by wide tracts of intercellular substance, but in 

 children are in such close apposition that the intercellular 

 substance only represents a slender trellis-work between the 

 cells, giving the whole an epithelium-like appearance. As the 

 sequator of the head of the bone is approximated, cells occur 

 which exhibit angular contours and short isolated processes. 



Still further down the cartilage cells are stellate, the processes 

 being relatively very long and occasionally branched, and 

 forming anastomoses. On thus proceeding towards the inser- 

 tion of the capsule, we arrive at a zone where the cartilage 

 cells gradually pass into connective-tissue corpuscles.* 



This is the region of the synovial membrane, and we here 

 meet with vessels that partly form arcades, and partly dip 

 more deeply, and enclose the serous canals in their meshes. 

 No superjacent layer of cells, however, can be perceived at 

 this point. It is only still further down, where the synovial 

 membrane extends as a free membrane from the glenoid cavity 

 upon the head of the bone, that superficial endothelial-like 

 markings become visible. 



* The importance of this fact in supplying an explanation of the 

 serous canals has been clearly pointed out by Bohm. In opposition to 

 Bohm, I have only to observe that the presence of stellate cartilage cells 

 is associated with proximity to the insertion of the synovial membrane, 

 and is not in relation with the mechanical relations of the cartilage, as 

 freedom from friction, etc. 



