OF ARTS AND SCIENCES. 



19 



dency to an arrangement in a linear series. The rows thus formed 

 run parallel with the long diameter of the bone, and are separated 

 from each other by the intercellular matrix, which consists of the par- 

 tially liquefied stroma. 



" It is thus that the future bone may be said to consist of a fasci- 

 culus of tubes filled with cartilage cells. This intercellular matrix 

 constitutes the primitive ossific rete, in which the calcareous salts are 

 first deposited. This first deposition having taken place, the cartilage- 

 cells are situated in cup-like, or rather cylinder-like, cavities. 



" During this time, however, the cartilage-cells, and the substance 

 immediately surrounding them, are likewise changed from the pres- 

 ence of calcareous matter. 



" The cells become smaller, and, in contracting, assume irregular 

 forms, and the septa separating the tubes in which they formerly 

 lay become more and more indistinct from the fulness of the cal- 

 careous deposition. Finally, a grayish mass is perceived, having 

 little regularity, and variegated in aspect by the presence of strangely 

 shaped bodies, the future Purkinjean corpuscles. But these processes 

 should be described a Uttle more minutely. During the calcareous 

 deposition, the aqueous portion of the tissue disappeai's, and, the size 

 of the whole being reduced, the cartilage-cells are brought nearer to- 

 gether ; the tissue, therefore, is much more compact, but has not lost 

 its original characteristics. The tubes of which we have spoken form 

 the concentric lamellcB, in which the corpuscles are regularly arranged ; 

 and thus a transverse section shows them to be solid cylinders instead 

 of hollow tubes as before the calcareous deposition. 



" The cartilage-cells are transformed into the Purkinjean or os- 

 seous corpuscles. This I have clearly observed, and have traced all the 

 phases of the change. Where the cells are in the cup-like cavities, 

 their nuclei are prominent. But as ossification proceeds they gradually 

 crumble away, and by the time ossific matter is deposited in the cell- 

 walls, little of them can be seen. The cells, however, remain in a 

 shrunken state, holding a concentric relation to a continuous cavity of 

 the tube, and which cavity is the Haversian canal. When the carti- 

 lage-cells begin to shrink, radiating lines are seen running from each, 

 and in reaching out in every direction, they meet and join those of 

 contiguous cells, and thus a connection is formed on every side. 



" The question now arises. What are these canaliculi ? Are they, 

 accordtng to Schwann, prolongations of the cartilage-cell membrane ; 



