3° CELL-NETWORKS. 



[sect. 



2 Higher Elementary Parts -the Formative Cells of toMch are 

 no Longer recognisable. 



i. Fibres, Fibrous Networks, and Membranes of Elastic and 

 Areolar Tissue. 



2. Fibrous Networks of the Transversely-striped Muscles. 



3- Fibres and Fibrous Networks of the Nervous Tissue. 



4- Tubes and Plexuses of the Blood and Lymph Capillaries. 

 5. Terminations of the Trachece of Insects. 



All these higher elementary parts possess essentially the same 

 properties as cells, especially growth in length, and thickness, absorp- 

 tion, metamorphoses, and excretion of materials, and, in part, con- 

 tractility, as also other functions, which, perhaps, can likewise be de- 

 monstrated in cells. Growth manifests itself very distinctly in the 

 circumstance, that all the above-mentioned elements immediately 

 after their formation are invariably much shorter and narrower 

 than at a subsequent period ; the absorption of material is proved 

 by the dependence of their functions upon the circulation, by the 

 phenomena of absorption in the capillaries of the lymphatics and 

 blood-vessels, and by the above-mentioned growth, which can only 

 be conceived as taking place by the absorption of materials into the 

 interior of these parts. A metamorphosis and excretion of mate- 

 rials may also be assumed along with these, as the well-known 

 peculiar products of decomposition in the muscles, the chants 

 of the muscular fibres and the nerve-tubes in altered nutrition and 

 activity, as also the capillaries which are continually givin- off the 

 plasma of the blood, sufficiently testify. The muscular fibril^ 

 possess contractility; and the processes in the nerve-tubes, which 

 although they possess their analogies in part in the functions of 

 the nerve-cells, are very peculiar, and, for the present, not to be 

 more definitely characterized. 



Literature of the Elementary Parts. -Besides Schwann's work, cited above 

 we may mention Kol^ker, Die Lehre von der thierischen Zelle, in Schleiden' 

 und Nagbli's Zeitschriftfiir wissenschaftl. Botanik. Part II. ,8 45 ^™ 

 lungsgescMchte der Gephalopoden, x8 44; and a Paper on Cuticular Structures 

 and Pores m Cell-membranes, in Transact, of the Wiirzb. Soc. Vol. viii. Eemak 

 Ueber exracellulare Entstehung thier. Zellen und die Vermehrung derselben 

 durch Thcdung,unduberEntsteh.des Bindegewebes, u. d. Knorpel, in Mini 



itu'l ! 4% L ; r ?J Q treatiSe ° f D0 ™ S ' cited ™ dei> E "c Tissue j 

 and the Embryological Monographs of Reichert, Bischofe, Vogt, Eemak and 



7fIM *7f %™T re , the T 1 ' 6 reCGnt — P-ative histological trea fees 

 £X.Med* Leychg, Leuckart, Carpenter, Huxley, Gegenbaur, Meissner, myself 



