188 Mr. Worsley-Benison on the 



liave a definite double name for these variations, but when using 

 this it is necessary not to forget that it is merely for classificatory 

 and useful purposes. 



G5. — On the Power of Movement in Plants. [Abstract.] 



By H. W. S. Worsley-Benison, F.L.S. 



(Eead October 12th, 1887.) 



Speaking first of the movements depending upon the proto- 

 plasm contained in plant-cells, or upon the presence of cilia, or 

 small hair-like processes on their surfaces, the lecturer remarked 

 that the motion of the contents of cells was of two kinds. In 

 rotation the current coursed only along the walls either spirally or 

 reticulately, the protoplasm making paths for itself in the cell- 

 sap, as in the stone-worts, Xitella and Clutra. In Chura the 

 inner layer of protoplasm rotated, carrying the nucleus with it ; 

 while the outer layer, or primordial utricle, immediately within 

 the cell-wall remained motionless, as did aLo the chlorophyll 

 grains. The motion in C/iara was at an angle with the wall, 

 while in Vallisneria it was parallel to and all round the wall, 

 carrying the chlorophyll grains with it. Cold retarded, heat 

 accelerated, but electrical currents stopped it. Jolting or prick- 

 ing the cell stopped it. The speed varied ; in the bristles on the 

 ovary of Circcea it completed the round in about one mhiute. 



In circulation, the protoplasm was hollowed out, and the 

 motion was in net-like currents, radiating from and returning to 

 the nucleus, passing in threads and bands through the cell-sap. 

 This was seen in the cells of the purple hairs of spiderwort, in 

 the cells of celandine, in nettle-hairs, and particularly in the 

 hairs of the buds of the marsh-mallow. Among the causes of 

 movement inside the cells of plants were constant chemical 

 changes, such as the formation paid evolution of carbonic acid, 

 and the formation of starch and the albuminoids ; these dis- 

 turbed the equilibrium of forces, and produced heat, and pro- 

 bably electrical currents, which in turn gave rise to forces of 

 astonishing magnitude, setting atoms and molecules in motion, 

 and representing an enormous amount of work. The absorption 

 of water alone developed an enormous force. The tension of 

 tissues or cells, due to unequal growth of layers; turgidity, or 

 the pressure of ccU-sap on the cell-wall, caused by attraction of 

 water by the substances dissolved in the cell-sap ; the diffusion 

 of gases ; and light and heat (as was well seen in the action of 

 these agents causing chlorophyll grains and Alga; spores visibly 

 to shift their positions), all brought about motion. 



