SECT. 103.] OSSEOUS SYSTEM. 195 



deposition of calcareous granules, whilst others are almost fully- 

 developed hone capsules, with pores and a more homogeneous 

 wall. 



I can thus support my above-mentioned assertion, of the deve- 

 lopment of the lacuna; from the cellular elements of the cartilage, 

 by what may be seen under normal conditions. In the last-men- 

 tioned places, I observed very frequently, also, half and completely 

 ossified mother-capsules, with from two to twelve included se- 

 condary capsules of the most beautiful description. 



The development of the medullary spaces and of the bone-marrow 

 is, in a certain measure, the last act in the transformation of 

 cartilage into bone. The medullary spaces originate not by the 

 coalescence of the cartilage-cells, but by the solution of the more 

 or less developed osseous substance, exactly in the same manner as 

 the large medullary cavities of the cylindrical bones. This can be 

 most distinctly proved by examining the diaphyses of a healthy or 

 rachitic bone, especially the latter. At the border of ossification 

 (fig. 84), the osseous substance is, for the distance of about 4-'" to 

 £'" , quite compact, without a trace of larger cavities, and is here 

 composed partly of ossifying matrix, partly of cartilage-capsules, 

 more or less changed into lacunas (see Micr. Anat, tab. iii.). Then 

 there come, first smaller, and further onwards, larger cavities, the 

 characters of which, in every respect, show most convincingly that 

 they do not owe their origin to the evolution or expansion of pre- 

 viously formed parts. They are bounded by very irregular con- 

 tours, which often appear as if eroded ; they are generally larger 

 than the cartilage-capsules, oval, or rounded and angular, and dis- 

 posed without any trace of regularity in the neAV-formed compact 

 bony substance. If the borders and bounding surfaces of these 

 spaces be narrowly examined, it is easy, in many cases, to recognise 

 more or less eroded bone-corpuscles, half projecting from or im- 

 bedded in the walls, and, between these, projections of the ossifying 

 matrix, so that not the slightest doubt can remain as to their 



origin. 



As in the diaphyses, so in the ossification of all the other car- 

 tilages, medullary spaces are formed by absorption within the half- 

 ossified substance, only it is to be observed that these spaces do 

 not exhibit the same direction and size in all the bones; but it is 

 unnecessary to dwell farther on this matter, since the conditions 

 of this primitive spongy substance is, in its main features, the 

 same at later periods. Still, it may be remarked, that probably in 

 many bones medullary spaces are developed directly from the 



o 2 



