CONNECTIVE TISSUE. 



249 



destitute of nuclei, the connection of which with each other and 

 with neighboring formations of the same nature is established 

 by the delicate spokes which traverse the intervening light rims. 

 After the infiltration with lime-salts is accomplished, an optical 

 differentiation of the lamella into single " osteoblasts " is pos- 

 sible in exceptional instances, when the lamella has the appear- 

 ance of being composed of polygonal fields. More frequently 

 the optical boundaries of the single osteoblasts fade, and only 

 central portions of the lamella remain intact in the form of 

 bone-corpuscles. In this case, therefore, a number of proto- 

 plasmic bodies have coalesced into a slightly curved lenticular 

 formation, a tissue-unit, the center of which is the bone-cell. 



yiM$OTSlSRr 



FIG. 102. VERTEBRA OF A HUMAN EMBRYO, FIVE MONTHS OLD. 

 HORIZONTAL SECTION. CHROMIC ACID SPECIMEN. 



M, medullary space, with central blood-vessels and medullary tissue ; J?, first-formed 

 globular territories, containing one or two central bone-corpuscles, with radiating offshoots. 

 The territories lie against the trabecula of the original calcified basis-substance of the 

 cartilage, F. Magnified 500 diameters. 



A number of such lenticular territories constitutes a single 

 lamella of bone-tissue. 



In the compact and the so-called intermediate substance of 



