116 



XXIX. 



PLANT MOVEMENTS. 

 A Paper read at Dover, 20th December, 1893, 



BY 



MR. GEORGE DOWKER, F.G.S., &c. 



An observer for the first time of a drop of water placed under 

 the microscope, seeing various monads, diatoms, or desmids in 

 motion, would naturally imagine that they belonged to the animal 

 kingdom, for that animals alone possess the power of locomotion 

 (although known to be a fallacy by the Botanist) is a very common 

 and almost popular belief. 



It must be confessed that the Naturalist in his endeavours to 

 explain these movements meets with many difficulties, particularly 

 as nearly all the old land marks are removed that separate the 

 animal from the vef/etabic kingdom, and he is compelled to acknow- 

 ledge that plant movements may be nearly related to animal 

 movements. 



In the animal kingdom motion is often dependent on certain 

 stimuli applied to ucivous centres and thence transferred to the 

 muscles. I say often, for there are certain ciliary movements 

 constantly in action in living animals, which arc not regulated by 

 nervous centres, or muscular motion ; the mucous membranes for 

 instance, or the currents of the cavities of sponges, lined with 

 living sarcode. 



Plants, like animals, have different modes of movement ; some 

 of these may be considered under the following heads : — 



1. Movements in the protoplasm of the cells, or sap movements. 



2. Movements of the growing points of the roots. 



3. Movements of the leaves and flowers. 



4. ]!k[ovements of sensitive plants. 



5. Movements of diatoms and desmids. 



6. Ciliary movements of zoospores. 



In a favorable view of a plant cell under the microscope, we 

 may observe constant currents, or movements, in the protoplasm, 

 (due I believe to the vital action of the cell), these are not merely 

 the fluid motion osmosis, but they appear to depend upon the action 

 of Jieat, light, and oxygen, upon the living protoplasm. The move- 

 ments are of two kinds ; in i\\ejlrst the granules in the protoplasm 



