196 OSSEOUS SYSTEM. [sect. I03. 



cartilage canals, since, at the border of ossification, a part at least 

 of the latter stands in direct connection with the spaces in the 

 bone; and further, that in many cases cartilage-elements, which 

 have not yet been completely converted into bone-capsules, are 

 involved in the process of resolution. With regard to this latter 

 point, it seems that in certain cases not one cartilage-cell is con- 

 verted into a real bone-corpuscle, with branched processes ; and it 

 may be recalled to mind, that many years ago Sharpey promul- 

 gated the opinion, that all bone-corpuscles in the bone formed 

 from cartilage are secondary formations, formed at the parietes of 

 the medullary spaces, — a view which is also maintained nearly in 

 the same manner in the recent investigations of H. Midler. 



The medullary spaces, however they arise, become filled with a 

 soft reddish substance, the foetal marrow. At first, this consists of 

 nothing but some fluid, and numerous rounded cells with one or 

 two nuclei and slightly granular contents. After a time, these 

 cells, which are quite identical with those occurring in certain 

 bones in the adult (see above), become developed in the usual 

 manner into connective tissue, blood-vessels, fat-cells, nerves, and 

 bone. The formation of the blood-vessels proceeds very rapidly, 

 so that, a short time after the development of the medullary spaces, 

 the bones already possess blood-vessels ; the fat-cells and the nerves 

 are more slowly formed, yet at the period of birth, they are very 

 readily seen in the large cylindrical bones. At this period the 

 fat-cells are but few in number, the marrow, in man, at least, 

 being still quite red from the presence of blood and the slightly 

 reddish-coloured marrow-cells. After birth the fat-cells gradually 

 multiply, till at last the marrow, in consequence of their great in- 

 crease, and of the disappearance of the marrow- cells, all of which 

 are finally resolved iuto the elements of the permanent marrow, 

 assumes its subsequent colour and consistence. A great part of 

 the cells of the new-formed marrow of developing bones are trans- 

 formed into bone, and thus serve to thicken the rudimentary bone- 

 lamellae, which took their origin from the cartilage. 



Disputes still prevail in various quarters about the development of the 

 lacunae from the cartilage-capsules, yet I .believe that my original description 

 (Ziirch. Mitth., 1847), which has been confirmed by Rokitaxsky and Virchow 

 (Wurzb. Verh. ii., and Arch. v. p. 431), is, as now modified, still the most 

 tenable. In the publication mentioned, I described the contents of the 

 bone-lacunse and cartilage-capsules as simple cell-contents, so that when 

 Virchow had demonstrated the direct transformation of plasm-cells into 

 bone-cells, it appeared almost impossible to harmonise my observations upon 

 rachitic bones with the latter. Now if, as held by Bemak and me, the ossifying 



