Placeholder text
The Journal of the Royal Horticultural Society, Vol. 35: Part I.; July, 1909 (Classic Reprint)
The Journal of the Royal Horticultural Society, Vol. 35: Part I.; July, 1909 (Classic Reprint)
0 - Default Title
Description
There are also numerous movements of protoplasm within cells, especially when the process of cell-division takes place. The well known streaming and rotation are continually going on and well seen in Chara; but these will not concern us now.
Other movements of organs are also the result of forces within the cells, and not the direct consequence of external agencies some of these will be referred to; but it is especially the movements resulting from stimuli of the surrounding physical conditions of life which I propose to deal with.
As soon as plants begin to grow, their organs are subjected to, and respond to, various external stimuli and the problem is to detect which is, or are - as there may be more than one - acting upon any organ at any one time. The chief influences are (1) light and (2) shade; t.e., really, varying degrees of light till perfect darkness may' occur. (3) Varying degrees of heat and cold. (4) Moisture in the air or soil. (5) Gravitation, always acting in a direction perpendicular to the earth's surface. (6) Contact with a resisting surface. (7) To the preceding may be added the internal influence of cellular growth, which produces external movements of growing shoots.
Organs may be developed under these influences without movement; but if their positions be altered, they will move or turn towards the source of the influence.
Both the tendency to respond to any of these influences may become a fixed and hereditary character, and take place when the original exciting influence is absent; and the structure itself caused by response may be, and usually is, hereditary as well; so that it may be formed completely or partially previous to the commencement of the action of the stimulus which had originally given rise to it.
See Cryptogamic Botany, by Bennett and Murray, pp. 422 and 442.
Product details
- Languages:
- Published: English , Original: English
- Number of Pages:
- 328
- Publisher:
- Forgotten Books
- Publication Date:
- 2017-12-01
- Weight:
- 590 g
Currently sold out