JOURNAL OF MICROSCOPICAL SCIENCE. 



DESCRIPTION OF PLATES VII & VIII, 



Illustrating Mr. E. A. Schafer's observations on the Struc- 

 ture and Development of Osseous Tissue. 



PLATE VII. 



Fig. 1. — Transverse section of human tibia, softened vrith picric acid and 

 stained with magenta glycerine. From near the surface of the 

 bone. H H, Haversian cauals, with their systems of concentric 

 lamellae ; in all the rest of the figure the lamellae are circum- 

 ferential, pf, ordinary perforating fibres ; e e, elastic perforating 

 fibres. Drawn under a power of about 150 diameters. 



Fig. 2. — Section through the middle of the humerus of a foetal sheep. 

 The entire bone was about 1 inch long, i c, The part of the 

 shaft which was primarily ossified in cartilage ; what remains of 

 the primal y bone is represented dark, and enveloped by the clear 

 secondary deposit. The areolae of the bone are occupied by 

 osteoblasts, with blood-vessels variously cut, and represented as 

 dark lines. One long straight vessel {Or) passes in advance of 

 the line of ossification far into the cartilaginous head ; most of 

 the others loop round close to the cartilage. At one or two 

 places in the older parts of the bone {c) elongated groups of 

 cartilage cells may still be seen, which have hitherto escaped 

 absorption, i m, The part of the bone that has been ossified 

 in membrane, i. e. in the osteoblastic tissue under the perios- 

 teum. It is well marked ofi' from the central portion, and is 

 bounded, peripherally, by a jagged edge, the projections of which 

 are indistinctly seen to be prolonged by bunches of osteogenic 

 fibres. A row of osteoblasts covers the superficial layer of the 

 boue. The subperiosteal layer is prolonged above into the 

 thickening {p), which encroaches upon the cartilage of the head of 

 the bone, and in which are seen, amongst numerous osteoblasts 

 and a few blood-vessels, the straight, longitudinal osteogenic 

 fibres (of) and some other fibres (/?/) crossing their direction and 

 probably representing the perforating fibres of Sharpey. The 

 main outlines of the figure were taken from a specimen that had 

 been stained lightly with carmine, but the details, which have been 

 represented with as near an approach to accuracy as possible, were 

 chiefly filled in from sections which had been stained with logwood. 



