20 GENERAL EVOLUTION". 



and phosphorus. In its mechanical aspect, as the material out 

 of which structures and tissues are made, it is called protoplasm. 



This substance exhibits two different phenomena of force- 

 energy, viz., motion and groiuth. Motion is exhibited by con- 

 traction and expansion, but which is the active state and which 

 the passive state is matter of question. Some physiologists regard 

 ''contractility" as the energetic state. Eadcliffe believes that 

 extension is the energetic condition, and contraction a rebound 

 or discharge of the extending force. He finds dead protoplasm 

 to be a dielectric, and believes that in life each muscular fibrilla 

 acts like a Leyden jar. It has been demonstrated that the outer 

 layer of the sheath of a muscular fibrilla is positively electrified in 

 life, while the cut extremities are negative, and it is shown by 

 Radcliffe that the inner side of the sheath becomes negatively 

 electrified by induction. The attraction of the opposite electrici- 

 ties on opposite sides of the sheath compresses and elongates it, 

 thus, according to his theory, producing muscular extension. The 

 nervous cells and tubes he believes to act in the same way ; the 

 difference being that the walls and sheaths are in a state which 

 prevents compression and extension. The phenomena of mus- 

 cular extension and nervous tension he believes to be terminated 

 by a discharge of the force, such as takes place in electrical fishes, 

 but in much smaller quantity. Thus motive force resides as a 

 form of electricity in protoplasm, and in highly organized animals 

 is specialized into neurism. 



As to growth-force, all its exhibitions may be reduced to cell- 

 division, cell-nutrition, and cell-origin. Cell-division exhibits 

 two prominent varieties. In both the cell nucleus first divides ; 

 in the ordinary mode, the cell-wall contracts at opposite points, 

 forming approaching plications, which, when they meet, divide 

 the cell. In the other mode or proliferation, the divisions of the 

 nuclei approach the cell- walls, which bulge opposite to them, 

 forming diverticula, which isolate themselves by opposing con- 

 tractions at the base, which meet as before. The nature of the 

 force thus displayed is as yet only speculative, and its demonstra- 

 tion will result largely from observation on cell-origin from homo- 

 geneous protoplasm. Eadcliffe suggests an ingenious theory. 

 He supposes that the protoplasm acquires an external layer differ- 

 entiated from the internal mass by exposure to and contact with 

 external substances, and that the electricity generated in the in- 

 terior is distributed on the under surface of this stratum. That 



