Se 214 AS tructural on Ph ysioligtcal Botany. 
~ ‘to exist -in the fortialion of starch in the grains of Soo in — pe 
case of some Algz; and the starch already formed in the chlorophyll Re ish, 
“of Monocotyledons and Dicotyledons may be produced by rays belong- 
ing to all parts of the spectrum ; but the action of the yellow raysis by 
-on the change in the tension of the tissues by which positive heliotropic 
/ 
- ments of the leaves of various plants, as the scarlet-runner and Oxalis. 
even disappears in a mixed blue light as in the dark. The green colour ‘ 5 Oa 
far the most powerful ; the red and the green have less power, while hala 
the blue, violet, and ultra-violet act very slowly. The action of light ~~ 
curvatures are brought about, belongs to the more refrangible (blue and 
_ violet) rays; the red and orange appear to be altogether inefficient. s z 
The same is the case with paratonic irritation and the periodical move- » 
On the movement of swarmspores the less refrangible (red and orange) 
rays act like darkness, while the direction of the movement is deter- = 
mined by the blue and by the still more refrangible violet and ultra- » 
violet rays. 
~ chemical properties in adjoining cells, the diffusiom of salts from cell to 
_ cell, their decomposition, the evolution of oxygen from cells con- 
between the surface of roots saturated with sap and the surface of the 
- protoplasm, and hence of the plant. (ie ae 5 
fe colouring of photographic paper, &e. But with reference to the vital Se 
- peocesses of the plant this term is inaccurate, and ought to be abandoned. Erte 
Light from other sources than the sun, as s that of lamps of various ms eo 
kinds or of a body glowing in an electric current (lime-light), appears, 
from observation, to have the same effect as sunlight, provided that the 
intensity and refrangibility of the rays are the same. 
The chemical processes within the cells of a plant, the molecular — 
movements connected with growth, and the internal changes on which 
the activity of the protoplasm depends—-whether exhibited in the 
formation of new cells or in motility--are probably connected with 
disturbances of the electrical equilibrium. The fluids of different 
taining chlorophyll, the formation of carbon dioxide in growing organs, 
and the process of transpiration :—all these vital processes must produce 
electrical currents ; although this fact has not yet been experimentally 
determined or accurately investigated. It has, however, been established 
that the internal tissue of land-plants is always electro-negative to the 
strongly cuticularised surface, and that a similar relationship subsists pes 
stem and leaves. Electrical currents which are not too strong only “e 
temporarily arrest the motility of protoplasm and the movements of the 
sensitive parts of plants, while stronger currents destroy the life of the —— 
in the combination of chlorine and hydrogen into hydrochloric aeid, tonte ot 
