A treatise on zoology . ated by the arrow. highest degree of clifFerenti Cartilage and bone may be lookedupon as specialisations of the generalscaftblding of connective tissue, whichpervades, so to speak, the entire bodyof a Craniate, aifording support to andbinding together the various parts ofthe oiganism. It is really in connec-tion with the muscular system that theconnective tissues have reached theiriation. The Craniata are elongated 58 GNA THOS TO MA TA 59 segmental animals, and correlated with this structure is the seg-mentation of their muscular system. In the lower forms, andin the em
A treatise on zoology . ated by the arrow. highest degree of clifFerenti Cartilage and bone may be lookedupon as specialisations of the generalscaftblding of connective tissue, whichpervades, so to speak, the entire bodyof a Craniate, aifording support to andbinding together the various parts ofthe oiganism. It is really in connec-tion with the muscular system that theconnective tissues have reached theiriation. The Craniata are elongated 58 GNA THOS TO MA TA 59 segmental animals, and correlated with this structure is the seg-mentation of their muscular system. In the lower forms, andin the embryos of the higher, the segmental character of thesomatic muscles is most distinctly shown. Now the connectivetissues are found to surround the myotomes, forming not onlyclosed boxes in which these lie, but also a lining to the body-walloutside and to the body-cavity within, and a sheath surroundingthe notochord and central nervous system. Thus a system oftransverse septa (myocomata), intersegmental in position, and of. Fig. 40. Diagram of the connective-tissue system in the trunk of a Craniate Vertebrate, showing therelation borne by the axial skeleton to the transverse and longitudinal septa, , wall ofabdominal coelom ; hd, basidorsal; hv, basiventral; , cut body-wall; , dorsal rib; i,intestine hanging in the coelom; iv, interventral ; m, transverse septum (myocomma); ws,mesentery ; , median dorsal septum; , median ventral septum ; nes, neural tube ;, notocliordal slieath ; , ventral or pleural rib; , neural spine ; ts, liorizontal view of left side, from which the septa have been partially removed. longitudinal, more or less tubular coverings, is formed. To thesemay be added a longitudinal vertical median septum, a longitudinalhorizontal septum (in Gnathostomes), and others of minor import-ance, completing the system of membranes in which the variousparts of the skeleton arise (Fig. 40). The true endoskeleton, in fact, is only the
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
