MINUTE STRUCTURE OF BONE. 



263 



sional occurrence of oval or flattened spheroidal bodies singly or in small groups near 

 the border of the layers, each with a lacuna in the centre (fig. 305). In some parts 

 the granular substance is obscurely fibrous, and transitions may be observed to the 



Fig. 304. MAGNIFIED VIEW OP A PERPENDICULAR SECTION THROUGH THE EXTERNAL TABLE OF A 



HUMAN PARIETAL BONE, DECALCIFIED (H. M tiller). 



At a, perforating fibres in their natural situation ; at b, others drawn out by separation of the 

 lamellae ; at c, the holes or sockets out of which they have been drawn (H. Muller). 



well-marked reticular laminae. The layers described appear principally to occur 

 near the surface of the compact tissue, and at the circumference of many of the 

 systems of concentric Haversian lamellae. 



Irregular layers of rounded bodies, apparently solid and without central cavity, 

 are also sometimes seen, and are well represented in figure 306. These layers are 



Fig. 305. SMALL PART OF A SECTION 

 THROUGH THE SHAFT OF A FEMUR (HUMAN, 

 16 YEARS) TAKEN A SHORT DISTANCE 

 FROM THE EPIPHYSIS. 230 DIAMETERS. 

 (Kolliker.) 



a, remains of calcified cartilage ; 6, bony 

 deposit in Howship's foveolse (absorption 

 spaces) ; c, subsequent deposit of lamellar / 

 bone. l/i 



met with chiefly near the surface of 

 the shaft of long bones, lying among 

 the circumferential laminae, and 

 apparently forming only part of a 

 circuit. They can occasionally be 

 recognised in a transverse section 

 as short curvilinear bands of peculiar 

 aspect, broader in the middle and 

 thinning away at the ends, appear- 

 ing here and there between the cut 

 edges of two ordinary circumferen- 

 tial laminae. 



Finally, spaces are occasionally seen in a section of bone, which are characterized 

 by an eroded outline, but in some cases they may be partially filled up by concentric 



