ON THE RELATION OF VEGETATION TO SEASONS. 
201 
When dug out of the earth, the roots are placed in the sun to dry, and are then 
put into sand or casks, where, if guarded from moisture, they may be preserved a 
considerable length of time, without being in any way injured in their quality. 
ON THE RELATION OF VEGETATION TO SEASONS*. 
Repose from growth seems periodically necessary to most plants, and accord- 
ingly we find there is no country without a season of growth and a season of rest, 
whether they are called by the name of winter and summer, or rainy season and dry 
season. This fact is connected with several considerations, to which it may be 
necessary to advert. What is about to be said has reference to the seasons of the 
north of Europe ; it is left to the reader to apply the observations to the climate of 
other parts of the world. In the winter we commonly say that all vegetation is at 
rest ; — that the sap ceases to flow, new parts to be developed, and old parts to 
enlarge ; but this is not exactly true. It appears, from experiment, that vegeta- 
tion is at all times more or less active, and that we ought to say, that it is languid 
in winter, and energetic in the spring and summer. The fact of many plants re- 
taining their leaves, of others swelling their buds, and of all forming an addition 
more or less considerable, to the points of their roots during winter, sufficiently 
attest the movement of the fluids, and the existence of vegetation even at that 
season. This is further proved by the well-known fact, that trees planted in the 
autumn become turgid with the fluid absorbed by their roots during winter ; and 
M. Biot has succeeded in obtaining a flow of sap from certain trees, even in the 
midst of that dreary season. But whatever power of attracting sap by its roots 
a plant may possess during winter, it is obvious that it has little means of parting 
with any part of it again by evaporation at that period of the year ; so that during 
the winter the whole of the tissue must acquire a state of turgidity, which will go on 
increasing till the leaves and new branches are developed to carry ofl" the sap, or 
decompose and assimilate it. 
This turgid state is eminently favourable to rapid growth when vegetation once 
resumes its activity ; for it acts as a force from behind, which continually presses 
on the new born tissue and causes it to expand. It is well known that, after very 
long winters, or when a plant has been prevented, by artificial means, from shooting 
at its usual season, its branches and leaves are developed with extraordinary vigour ; 
a circumstance which has been ascribed to accumulated irritability , but which is, in 
fact, owing to the turgid state of the tissue. It is when the temperature of the 
* Extracted from the part Botany^ published under the superintendence of the Society for the Diffusion 
of Useful Knowledge, attributed to the pen of Dr. Lindley. 
VOL. III.^ NO. XXXIII. D D 
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