62 



THE CONNECTIVE TISSUES. 



[CH. v. 



Fig. 85. Bone-corpuscles with their processes as 

 seen in a thin section of human bone. 

 (Rollett.) 



bone immediately surrounding it, and one lacunar corpuscle com- 

 municates with another, and with its surrounding district, and 



with the blood-vessels of 

 the Haversiau canals, by 

 means of the minute 

 streams of fluent nutrient 

 matter or lymph which 

 occupy the canaliculi. 



It will be seen from the 

 above description that bone 

 is essentially connective 

 tissue, the ground-sub- 

 stance of which is impreg- 

 nated with lime salts. The 

 bone-corpuscles with their 

 processes, occupying the 

 lacunae and canaliculi, 

 correspond exactly to the 

 connective-tissue corpuscles 

 lying in branched spaces. 



Lamellae of Compact 

 Bone. In the shaft of a 

 long bone three distinct sets of lamellae can be clearly recognised. 



1 . Circumferential lamellae ; which 

 are most easily traceable just beneath 

 the periosteum, and around the 

 medullary cavity, forming around the 

 latter a series of concentric rings. At 

 a little distance from the medullary 

 and periosteal surfaces (in the deeper 

 portions of the bone) they are more or 

 less interrupted by 



2. Haversian lamellae, which are 

 concentrically arranged around the 

 Haversian canals to the number of 

 six to eighteen around each. 



3. Interstitial lamellae, which con- 

 nect the systems of Haversian lamellae, 

 filling the spaces between them, and 

 consequently attaining their greatest 

 development where the Haversian 

 systems are few, and vice versd. 



The ultimate structure of the lamellae is fibrous. If a thin 

 film be peeled off the surface of a bone, from which the earthy 



Fig. 86. Thin layer peeled off 

 from a softened bone. This 

 figure, which is intended to 

 represent the reticular struc- 

 ture of a lamella, gives a better 

 idea of the object when held 

 rather farther off than usual 

 from the eye. x 400. 



(Snarpey.) 



