i8o 



PRACTICAL HISTOLOGY. 



[XIII. 



V B 



T.S. and L.S. The sections, however, must not be too thin. L.S. 



tire the most instructive, and are mounted in glycerine-jelly. 



(a.) Observe that the blood- 

 vessels lie in the Haversian 

 canals, and follow the arrange- 

 ment of the latter (fig. 152). 

 If the marrow of the bone be 

 preserved, fine blood-vessels 

 may be seen in it. Perhaps 

 "perforating vessels' 7 lying in 

 Volkmann's canals may be 

 noticed, especially in transverse 

 sections. 



6. Cancellated Bone (L and 

 H). In the vertical section of 

 the head of a long bone showing 

 articular cartilage a view of the 

 open lattice-work will be ob- 

 tained (Lesson XIV. 3). Or a 

 T.S. may be made across the 



head of a long bone ' e ' ff '> a 

 femur, preferably of a young 



animal. Stain a section in 

 haematoxylin, picro-carmine, or 



COsin-logWOOd, and mount it ill 

 <" r lycerine-ielly. 



(a.) (L) Note the network of 



osseous trabeculse (fig. 153) bounding the spaces or cancelli. In 

 the latter lies red marrow, and on their walls are osteoblasts. In 



the centre of some of the 

 trabeculse may be seen a 

 deeper stained irregular bar, 

 the remains of calcined carti- 

 lage (fig. 153, CC). On the 

 calcified cartilage is deposited 

 osseous tissue. 



(6.) (H) In each trabecula 

 note the fibrous matrix and 

 the bone-corpuscles. In the 

 interior of some of the tra- 

 beculse the remains of un- 

 absorbed calcified cartilage. 

 Note also how the osseous 

 tissue with spherical bulgings advances upon the calcified cartilage. 

 By carefully shading the light, it will be seen that a more or less 



FIG. I52.-L.S. Injected Bone. P. Perios- 

 teum ; B. Bone; V. Blood-vessels. 



FlG. 153. Cancellated Bone. C. Canceling; 

 T. Trabecula; CC. Calcified cartilage; B. 

 Bone ; 0. Osteoblast. 



