CELLS. 



Plagiostome fishes (see Leydig, ' Beitnige zur mikr. Anat. u. 

 Entwickel. d. Rochen u. Haie.,' Leipzig, 1852), the pigment 

 cells of the lamina fusca, pin 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 (II. Meyer, 

 ' Zeitschrift fiir wiss. Zool./ Bd. i, st. 178). 



b. The elastic fibres, fibrous networks, and fibres. 



c. The fibres of connective tissue, the networks of connective 

 tissue (reticulated- connective tissue), and the membranes com- 

 posed of connective tissue (homogeneous connective tissue) . 



d. The transversely striated muscular fibres and muscular- 

 fibre networks. 



e. The nerve-fibres and nerve-fibre networks. 



f. The capillary plexuses of the blood-vessels and lymphatics. 



y. The trachea and tracheal plexuses of the invertebrata. 



All these higher elementary parts possess essentially the same . 

 properties as cells, especially growth in length and thickness, 

 absorption, metamorphosis, and excretion, and to some extent 

 contractility ; together with other functions which may perhaps 

 also be demonstrated in cells. Their growth is manifested by 

 the fact, that all, without exception, are much shorter and 

 narrower immediately after their formation than subsequently ; 

 their absorptive powers, by the dependence of their functions 

 upon the circulation, by the phenomena of resorption in the 

 lymphatics and blood-vascular capillaries, and by the above- 

 mentioned growth, which can only take place by the reception 

 of substances into their interior. A metamorphic and an excre- 

 tive power must be assumed to exist in them ; it is testified by 

 the well-known peculiar products of decomposition of the 

 muscles, and also by the continual transmission of blood-plasma 

 through the walls of the capillaries. The muscular fibrils 

 possess contractility, and the processes in the nerve-fibres, 

 though very peculiar, and at present not to be defined more 

 nearly, may nevertheless in some respects be compared to the 

 functions of the nerve-cells. 



[With regard to the tracheae, which are placed here only for 

 completeness' sake, I long since found that their terminations 

 are formed by the coalescence of stellate cells into tubes, in 

 which the original cell-contents either remain or become de- 



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