484 



OF NUTRITION. 



[Fig. 118. 



which these rows of cells are se- 

 parated, ossific matter is at the 

 same time deposited ; and when 

 the spaces communicate with each 

 other, so as to form a network 

 receiving blood-vessels, this pro- 

 cess takes place with greater ra- 

 pidity. It is then observed that 

 few of the original cells are to be 

 seen in the cavities ; which are 

 chiefly occupied by a quantity of 

 new substance resembling the 

 formative blastema, from which 

 all the tissues are evolved. The 

 original cells appear to have be- 

 come flattened against the walls 

 of the cavity ; and to have coa- 

 lesced into the osseous lamellae, 

 which are gradually formed con- 

 centrically within it. In these 

 lamellae are included the nuclei 

 of the cells ; which are at first 

 granular, but which subsequently 

 remain as hollows in the osseous 

 deposit ; and from these, the mi- 

 nute tubuli afterwards shoot out.* 



[The nucleated cells of temporary- 

 cartilage are small, and pretty uni- 

 formly scattered through a sparing, 

 homogeneous intercellular substance. 

 The nuclei are granular, and large 

 compared with the cells, which are 

 distinguished from the surrounding 

 substance principally by their trans- 

 parency around each nucleus (Fig. 

 118,1, 1'.) 



In the vicinity of the point of ossi- 

 fication, (for example, in one of the 

 long bones,) a singular change is ob- 

 served. The cells are seen to be gra- 

 dually arranging themselves in linear 

 series, which run down, as it were, 

 towards the ossifying surface. The 

 appearance they present on a vertical 

 section is represented in Fig. 118. At 

 first their aggregation is irregular, 

 and the series small (2,2'); but, nearer 

 to the surface of ossification, they form 

 rows of twenty or thirty. These rows 

 are slightly undulated, and are separated from one another by the intercellular substance. 

 The cells composing them are closely applied to one another, and compressed, so that 

 even their nuclei seem in many instances to touch; the nuclei themselves are also flat- 

 tened, and expanded laterally. 



The lowest rows dip into, and rest in deep narrow cups of bone, formed by the osseous 

 transformation of the intercellular substance between the rows. These cups are seen by 

 a vertical section in fig. 118, 3, 3'. As ossification advances between the rows, these 



* See the account of Mr. Tome's investigations, contained in Todd and Bowman's 

 Physiological Anatomy, pp. 117 122. These seem to correspond, in their essential 

 points,, with those of Gerber (General Anatomy, p. 184). 



Vertical section of Cartilage near the surface of ossifi- 

 cation; 1, ordinary appearance of the temporary cartilage; 

 1', portion of the same more highly magnified ; 2, the cells 

 beginning to assume the linear direction; 2', portion more 

 magnified ; opposite 3, the ossification is extending in the 

 intercellular spaces, and the rows of cells are seen resting 

 in the cavities so formed, the nuclei being more separated 

 than above ; 3', portion of the same more highly magnified. 

 From a new-born rabbit which had been preserved in 

 spirit.] 



