General principles of zoology . ganic constituents,the most important is calcicphosphate, 84$; in smallerquantities, combinations offluoric, chloric, carbonic acidsand magnesia. Morphologi-cally the matrix is composedof the bone lamellae (), whose arrangement isdetermined by the surfacespresent in and against thebone. In a hollow bone(like that of the upper armor of the hand) there is onesurface given by the externalborder to which a fibrous,skin, the bone-skin or perio-steum, is closely applied;the presence of the marrow-cavity necessitates a secondsurface. Finally, the solidmass of the
General principles of zoology . ganic constituents,the most important is calcicphosphate, 84$; in smallerquantities, combinations offluoric, chloric, carbonic acidsand magnesia. Morphologi-cally the matrix is composedof the bone lamellae (), whose arrangement isdetermined by the surfacespresent in and against thebone. In a hollow bone(like that of the upper armor of the hand) there is onesurface given by the externalborder to which a fibrous,skin, the bone-skin or perio-steum, is closely applied;the presence of the marrow-cavity necessitates a secondsurface. Finally, the solidmass of the bone is permeated by the Haversian canals,which run chiefly in a longitudinal direction, united into anetwork by cross or oblique canals, and serve for thecourse of blood-vessels. Since now the bone lamellaearrange themselves parallel to the surfaces mentioned, twosystems may be distinguished in cross-section, the funda-mental lamellae and the Haversian lamella. The formerare arranged parallel to the surface of the FiG. 42.—Cross-section through the humanmetacarpus. a, surface of the perios-teum ; ^, surface of the marrow-cavity ;<:, cross-sections of the Haversian canalsand their system of lamellae ; d, funda-mental lamellae; e, bone-corpuscles.(After frey.) GENERAL HISTOLOGY. and of the marrow-cavity and form a mantle of concen-tric layers around the marrow-cavity. Into this ground-work enter the Haversian canals with their lamellae, de-stroying and superseding the fundamental lamellae comingin their way. The Haversian lamellae are concentri-cally arranged around the lumen of the Haversian canalsjust as are the fundamental lamellae around the marrow-cavity. Formation of Bone.—The stratification of bone iscaused by its mode of origin. \Yhere the bone bordersupon the Haversian canals, the marrow-cavity, and theperiosteum, there is transiently or permanently an epithe-lial-like layer of cells, ostcoblasts, which secrete ontheir surface the bone-substance. Ce
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1896
