00 MANUAL OF HISTOLOGY. 



ways easily recognized, and, in fact, have often been ignored 

 by writers of anatomical text-books. They were not detected 

 for a long time, because the capsules in which they are em- 

 bedded received all the attention, and were even called bone- 

 corpuscles. But when it was discovered by Virchow that 

 these bodies had nuclei, and that they could be separated, to- 

 gether with their processes, from the bone, it was supposed 

 that the nutrition of the tissue was maintained through them, 

 acting in the capacity of hollow tubes. This view Virchow at 

 one time supported. Subsequently it was discovered that in- 

 jection fluids could be forced into the canaliculi and round 

 about the corpuscles, so that three facts became assured : (1) 

 the existence of capsules in the bony substance with radiating 

 and anastomosing passages, the lacunae and canaliculi ; (2) the 

 presence of nucleated and branched corpuscles in the lacunae ; 

 and of spaces (3) about the nucleated corpuscles and their 

 processes, suitable for the movement of fluids designed for the 

 nutrition of the part. 



The structure of bone then became clear, and its similarity 

 with other connective substances well established. These bony 

 canaliculi extend to the wall of the Haversian canal, the great 

 channel conveying the blood-vessels and larger lymphatics. 

 Thus a lymph-canalicular system permeates the bone in close 

 connection with the blood-vessels, bathing every bone-cor- 

 puscle. 



When a cross-section is made of any long bone, it will be 

 observed that most of the lamellae have a concentric arrange- 

 ment about each Haversian canal (Fig. 35, b). But it will also 

 be seen that there are other groups of lamellae whose arrange- 

 ment is slightly different. For example, at the periphery of 

 the bone their direction is parallel with the surface. 



Such lamellae may be represented at a. They are known as 

 the intermediate or circumferential (Tomes and De Morgan). 

 Another group, only partly encircling each canal, is known as 

 the peripkeric or interstitial, c. The first mentioned, imme- 

 diately about the canal, are the concentric, b. 



Schaefer believes with Sharpey that each lamella consists of fibres crossing 

 each other diagonally, and separated on either side by a homogeneons layer. 

 According to Von Ebner, the peculiar cross striations belong only to Canada 

 balsam preparations that are old. These markings are due to the peculiar 

 refractive power of the balsam which fills the canaliculi 



