236 



CONNECTIVE TISSUE. 



were visible, separated from each other by finely granular or 

 homogeneous shining masses. 



The same condition was also observed in transverse sections. 

 I found in the center of a system of lamellae solid, finely granular 

 corpuscles, which, in both an upward and downward direction, 

 blended with the transverse cavities of bone or with the calibers 

 of vessels. (See Fig. 94.) 



The conclusions I arrived at are as follows: The material 

 contained in the vascular canals is, with advancing growth, 

 transformed into bone, leaving only the blood-vessel behind. 



FIG. 94. TRANSVERSE SECTION OF THE INJECTED TIBIA OF A GROWN DOG. 

 CHROMIC ACID SPECIMEN. A COMMON SYSTEM OF LAMELLAE INCLOSES 

 Two SMALLER SYSTEMS. [PUBLISHED IN 1873.] 



V, the central vascular canal, with a capillary blood-vessel; JBC, a central solid corpuscle 

 sprung from a former blood-vessel. Magnified 800 diameters. 



After a time, a transformation of the blood-vessels themselves to 

 bone-tissue takes place by a solidification of the hollow proto- 

 plasma of the wall of the vessels, and thereupon a differentia- 

 tion into bone-corpuscles and bony basis-substance. 



DEVELOPMENT OF BONE. 



It is a fact, well known for centuries, that the skeleton in the 

 embryo is first formed of cartilage. The main question at all 



