6o 



ELEMENTS OF HISTOLOGY. [Chap. vn. 



origin. 







At the extremity of the shaft, however, the 

 spongy bone is all 

 endochondral bone, 

 and it continues to 

 S^^$^3i*< a g row i n * the inter- 

 S^t^^jjjf ' mediate cartilage as 

 ^.^(^^, stated above, as long 

 as the bone as a whole 

 saa^fl grows (Fig. 36). 



Of course the parts 

 of this spongy bone 

 nearest to the centre 

 of the shaft are the 

 oldest, and ulti- 

 mately disappear by 

 absorption into the 

 central marrow 

 cavity. In the epi- 

 physis the spongy 

 bone is also endo- 

 chondral bone, and 

 its formation is con- 

 nected with the deep 

 layer of the articu- 

 lar cartilage. 



Underneath the 



periosteum and on 

 the surface of the 

 spongy endochon- 



cartilage; c, zone, in which the calcined dral DOne at the 

 trabeculse of cartilatre become erradually in- o-vfivirm+v rvf \\\(* 

 vested in osseous substance, shaded light in extremity OI lilt! 



shaft, the periosteal 

 bone is represented 

 only as a thin layer, 

 extending as far 

 to the margin of the 



ig. 



Femur of Babbit, through the parb in 

 which the intermediary cartilage joins 

 the end of the shaft. 



a. Intermediary cartilage; 6, zone of calcified 

 cartilage; c, zone, in which the calcified 



, 



the figure ; the spaces between the trabecuhe 

 contain marrow, and the capillary blood- 

 vessels are seen here to end in loops; d, in 

 this zone there is more bone formed : the 

 greater amount the farther away from this 

 zone. (Atlas.) 



as the periosteum reaches, e.g., 

 articular cartilage. 



