EOXE. 



Fig. LV. 



are opened by absorption, and the granular bodies contained within them (i.e. 



the proper cell-bodies) produce by fissi- 

 parous multiplication the granular osteo- 

 blastic cells which succeed them. On 

 the other hand, Love"n* has suggested, 

 and, as I think, with more probability, 

 that the osteoblastic corpuscles properly 

 belong to the vascular processes of the 

 subperiosteal tissue, which, as already 

 stated, penetrate the newly formed bone 

 and spread throughout its cavernulated 

 structure. The excavation and removal 

 of the cartilage, as well as the partial 

 absorption of the walls of the bony cavi- 

 ties, is no doubt effected by this tissue, 

 and the abundant osteoblastic cells which 

 appear in it are most probably derived 

 by descent from similar cells equally 

 abundant beneath the periosteum. The 

 cells or corpuscles in question, in what- 

 ever way produced, are disposed in a layer 

 or layers upon the walls of the secondary 

 or medullary spaces, in immediate con- 

 tact with the new osteogenic deposit, 

 which here, as in the intramembranous 

 ossification, they probably secrete. Here 

 too the osteogenic substance is finely 

 reticular, and retains that character when 

 calcified ; for the secondary bony deposit 

 is formed in layers made up of finely 

 reticulating fibres, like the lamellae of 

 perfect bone shown in fig. XLV. On a 

 careful inspection, and M'ith a certain 

 adjustment of the light, fine striae may 

 be seen in many parts indicating the 

 obliquely decussating fibres of the newly 

 formed laminae. The structure in some 

 measure reminds us of the secondary 

 deposit inside the oblong cells of the 

 wood of coniferous trees, in which the 

 ligneous matter is arranged in fibres, or 

 rather in fine lines, running obliquely 

 round the wall of the cell and crossing 

 one another in alternate layers. 



The lacunas are formed, as described 

 in the intramembranous ossification, by 

 some of the granular corpuscles becom- 

 ing imbedded in the osteogenic sub- 

 stance, and inclosed in a cavity formed 

 round them by its further deposit. La- 

 cunae formed from cartilage-cells exist 

 but very scantily. Examples occur in 

 articular cartilage, and in that of the 

 pubic symphysis, when, as commonly 

 happens in mature life, the part of these 

 tissues adjoining the bone is encroached 

 on by a species of ossification, as noticed 

 at page xcix. The ossifying process in 

 this case is mere calcification of the 

 cartilage, and stellate lacunae, not inter- 



Fig. LV. THIN LONGITUDINAL SECTION OP 

 THE GROWING END OF THE SHAFT OF THE 

 METATARSAL BONE OF A SLINK CALF, 

 MAGNIFIED. 



The upper part of the figure shows four 

 groups of cartilage cells, with calcified matrix 

 between them forming the walls of four 

 primary areolse filled as yet by the original 

 cartilage cells, except at the lower part where 

 these are replaced by granular corpuscles. 

 Lower clown are two oblong spaces (secondary 

 or medullary cavities) ; one, indicated by d, 

 is nearly filled by granular corpuscles and 

 vessels, the other is vacant. The walls of 

 these spaces are beginning to be lined with 

 secondary osseous deposit, shown in the 

 figure as a lighter layer, &, &, and b ; c, c, 

 and c, are corpuscles about to be imbedded 

 in the ossifying substance and inclosed in 

 laminse; g, a cartilage cell of which the body 

 has shrunk from the inside of the capsule. 

 After H. Miiller and Kolliker. 



* Studier och Undersokningar ofver Benvafnaden. Stockholm. ]863. 



