256 ON THE STRUCTURE OF OSCILLATORIiE. 



If plants exist without these three general attributes of life, 

 then let me ask, in order to give but a few instances, why do 

 we witness in many plants a kind of sleep, or exhaustion and 

 subsequent recovery by rest ? Why does the (Eiiothera 

 biennis open its flowers only towards evenmg, remaining open 

 during night, and fade the next morning if the sky is clear 

 and bright? Why, on the contrary, does the Drosera rotun- 

 difolia open its flowers only under the stimulus of the strong 

 light and warmth of mid-day ? Why do the flowers of 

 NymphcBa alba not only close but sink beneath the water 

 during the whole night, and rise only the next morning above 

 the surface ? Why do the leaves of the Mimosa pudica, sensi- 

 tiva, and of a number of this class of plants, visibly contract 

 when touched ? Why do the filaments of Berberis vulgaris, if 

 touched on the side next to the pistil, fly immediately towards 

 the stigma ? Why do they lose this property if exposed for 

 a short time to the vapour of chlorofoi'm ? Why, indeed, 

 does it return after a certain interval if the exposure has not 

 been too prolonged? — (Mic, Journ,, No. iii., p. 250.) 



How exquisite must be the irritability of the Dioncea musci- 

 j)ula, the leaf of which, or rather a part of it, folds up, even 

 if a little insect alight upon it ? And why does it not relax 

 its grasp but when the little prisoner has ceased to make any 

 efforts for his delivery ? Why do the five stamens of Par- 

 Jiassia palustris bend themselves forward and over the stigma, 

 and even, secundum ordinem, first one, after it has risen and 

 bent back, followed by a second, this by a third, and finally 

 by the remaining two at the same time ? 



Many other instances of sensibility, irritability, and instinct 

 observable in plants might be adduced if needed, but surely 

 because these phenomena are witnessed only in a limited 

 number of plants, in so striking a manner, is no reason that 

 we should ignore them, neither can the visibility of their 

 effects decide the question of their existence, nor is it neces- 

 sary that all parts of plants should possess them in the same 

 degree. It has already been stated that there are animals 

 without a nervous system, without a head or distinct sexual 

 organs ; though, as a rule, the presence of a nervous system, 

 a head, &c., forms one of the most striking characters of an 

 animal, yet their absence, in some instances, does not eo ipso 

 exclude them from the animal kingdom. In the same manner 

 all parts of animals are not alike endowed with sensibility, as, 

 for instance, the epidermis and other epidermal structures, 

 as hairs, nails, &c. The other negative qualification attributed 

 to a plant, viz., tlie absence of voluntary motion, appears to me 

 equally erroneous. 



