50 CALCIFICATION. 



eareous infiltrations of a purely local character, beginning ^Yitll 

 physiological examples of the process. 



§ 52. True bone tissue originates as follows : — In a con- 

 nective tissue, richly provided with capillaries, which map it 

 out into vascular territories or islets of parenchyma, a compact 

 matrix is developed ; it first appears in the centre of each territory ; 

 at the point, therefore, which is farthest from the blood-current. 

 The cells, which are already assuming a stellate form, become 

 enclosed in this matrix at regular intervals, the matrix itself 

 undergoing impregnation with earthy salts. This typical series 

 of phenomena underlies all ossification, whether in membrane 

 or in cartilage. In either case the medullary spaces are first 

 sketched out in this way. The regular repetition of this sequence 

 of matrix- formation, enclosure of cells and calcification, leads on 

 the one hand, to the production of compact bone tissue disposed 

 in concentric laminae round the blood-vessels ; while, on the other, 

 it narrows the original medullary cavity to the size of a Haversian 

 canal. For the details of the process I refer the reader to text- 

 books of normal histology. For us the important point is that the 

 earthy salts are first deposited along those neutral lines which 

 may be looked upon with equal justice as the limitary or the axial 

 lines of the vascular territories. It need hardly be said that these 

 lines cross each other at certain points, and must therefore form a 

 network resembling that formed by the capillaries themselves ; 

 this inference being fully corroborated by the examination of an 

 osteophyte at an early stage of its growth, or of a cylindrical 

 bone at its ossifying border, where it adjoins the cartilage.'* 

 We cannot but recollect that in the parenchyma of other con- 

 nective tissues the lymphatics stand very constantly in a similar 

 relation to the capillaries. I pointed out, as early as the year 

 1859,t that the lymphatics in the tail of the tadpole were in- 

 variably situated in those parts of the parenchyma which were 

 farthest from the vessels. Since that time the course of the 

 capillary lymphatics has been repeatedly investigated, and the 

 above statement has been again and again confirmed. (Cf. 

 Vo7i Recklinghausen, '* The Lymphatics and their Relation to the 

 Connective Tissue," Plate I. fig. 1.) This arrangement is 



* See " Osseous System," Exostosis. 



t Be Vasonim Genesi. Inaugural Dissertation. Berlin. 



