70 ^ GENERAL ANATOMY OF THE TISSUES. 



2. Metamorphosed cells, which have more or less altered their original 

 structure. To these belong : 



a. The horny scales : flattened, polygonal, or fusiform : their membrane 

 being fused into one mass with the contents. In the epidermis, the 

 laminated pavement epithelium, the hairs and nails. 



b. The contractile fibre cells: fusiform, slightly flattened, considerably 

 elongated cells, whose membrane, together with its soft solid contents is 

 changed into a contractile substance. In the smooth muscles. 



c. The tubules of the lens : very much elongated cells, with viscid, 

 albuminous contents. 



d. The prisms of the enamel: greatly elongated, prismatic, and strongly 

 calcified cells. 



e. The lone cells : thickened cells with pore canals which have coa- 

 lesced with the homogeneous matrix of the bones and anastomose by 

 means of excavations in it. 



/. The transversely striated muscular cells : large polygonal cells, 

 whose contents have become metamorphosed into a transversely striated 

 tissue, such as is found in the transversely striated muscular fibre. In 

 the endocardium of ruminants. 



B. HIGHER ELEMENTARY PARTS. 



19. The higher elementary parts correspond, genetically, to a whole 

 series of the simple ones, and it is the cells only, so far as we know, 

 which possess the faculty of producing them. The manner in which this 

 takes place varies. Either the cells while they coalesce retain their cellu- 

 lar nature, and to a certain extent their independence, in which case we 

 have, according as they are fusiform or stellate cells, cell-fibres or cell- 

 reticulations ; or the cells in uniting totally surrender their indepen- 

 dence, in which case they form, if they are arranged in lines, elongated 

 elementary parts ; or are united by many offsets, networks ; or are 

 fused together upon all sides, membranes. The two former of these 

 again, according to the kind of modification undergone by the contents 

 of the united cells, appear either as fibres, bundles offibrilla? and tubes, 

 or as fibre-networks and tubular plexuses. Since all these elementary 

 parts will be spoken of at length afterwards, among the tissues, we may 

 here simply enumerate them as follows. They are : 



a. The cell-fibres and cell-networks. To these belong a part of the 

 nuclear fibres of authors, the cartilage cells of certain Plagiostome 

 fishes (see Leydig, " Beitrage zur mikr. Anat. u. Entwickel. d. Rochen 

 u. Haie.," Leipzig, 1852), the pigment cells of the lamina fusca, pia 

 mater, and of Batrachian larvae, the networks of the nerve cells in the 

 brain of the Torpedo (R. Wagner), the fatty substance of the Lepidoptera 

 (H. Meyer, "Zeitschrift fur wiss. Zool.," Bd. i. st. 178). 



