. A manual of zoology. Zoology. 7S GENERAL TRINCirLES OF ZOOLOGY arrange tliemsclves parallel to the surfaecs mentioned, two systems may be distinguished in eross-seetion, the fiiiidainfiilal UdiicIUc and the Hcivcrsia)i lamdhc. The former are arranged parallel to the surfaee of the periosteum and of the niarrow-eavity and form a mantle of coneentric layers around the marro\v-ca\"itv. Into this groundwork the Haversian canals with their lamelke enter, destroying and superseding the fundamental lamella: coming in their way. The Ha\ersian lamelhc are concentrically arranged around the lumen
. A manual of zoology. Zoology. 7S GENERAL TRINCirLES OF ZOOLOGY arrange tliemsclves parallel to the surfaecs mentioned, two systems may be distinguished in eross-seetion, the fiiiidainfiilal UdiicIUc and the Hcivcrsia)i lamdhc. The former are arranged parallel to the surfaee of the periosteum and of the niarrow-eavity and form a mantle of coneentric layers around the marro\v-ca\"itv. Into this groundwork the Haversian canals with their lamelke enter, destroying and superseding the fundamental lamella: coming in their way. The Ha\ersian lamelhc are concentrically arranged around the lumen of the Haversian canals just as the fundamental lamelke are around the niarrow- cavitv and beneath the periosteum. Formation of Bone.—The stratification of bone is caused by its mode of origin. Where the bone borders upon the Haversian canals, the marrow-cavity, and the periosteum, there is transiently or permanently an epithelialdike layer of cells, osteoblasts, which secrete the bone-substance on their surface, which, as mth all similar conditions, gives the substance a stratification. Certain cells in the matrix participate in this secretion, and here give rise to the bone-cor- puscles, which are distinguished from the cartilage-cells by their numerous processes ramifying through the matrix. The processes of a bone-corpuscle branch and unite with the neighboring cells through fusion of the processes, an arrangement most beautifully seen in dried bone, because here the cavities and the canals of the matrix are filled with air. In spongy bone the structure is simplified since the Haversian canals with their lamelke, and often the stratifica- tion of the ground lamelkr, are lacking. Special modifications of bone are found in the substance of fish scales and in the dentine or ivory of teeth. Blood and Lymph, here treated in connection with the connective tissues, are in reality not tissues at all, but nutritive lluids. Two kinds of nutritive fluids occur in the verte- N—^^&
Size: 1732px × 1443px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
