TLA NT CONSCIOUSNESS. 



445 



variation in their environment, and so are able to vary their actions 

 accordingly. 



The commonly adopted opinion that plants cannot be classed among 

 conscious agents has never been proved, although perhaps to most people 

 it may seem self-evident. Wordsworth did not think so, for he said : 



It is my faith that every flower which blows 

 Enjoys the air it breathes. 



But those acquainted even superficially with the habits of plants will 

 scarcely deny that they have the power of adapting themselves to circum- 

 stances, and have many movements that are the very reverse of automatic, 

 which point to the idea that they are endowed with a power something 

 higher than mere instinct. Numerous instances will occur to their minds 

 of sensibility as fully developed in the plant as in the animal, which 

 in the latter is, without doubt, the outcome of conscious perception and 

 thought brought into action through the medium of the brain. 



Take, for instance, that wonderful plant, the Mimosa, sensitive not 

 only of the most delicate touch, but, like most other genera, of the 

 approach of darkness or of even a shadow thrown upon it, of which the 

 poet says : 



Weak with nice sense, the chaste Mimosa stands, 

 From each rude touch withdraws her timid hands ; 

 Oft as light clouds o'erpass the summer glade, 

 Alarmed she trembles at the moving shade, 

 And feels, alive through all her tender form, 

 The whispered murmurs of the gathering storm ; 

 Shuts her sweet eyelids to the approaching night, 

 And hails with freshened charms the rising light. 



Many species of Mimosa possess this property, and, indeed, most of 

 the genus in a greater or less degree. They have their leaves beautifully 

 divided, again and again pinnate, with a great number of small leaflets of 

 which the pairs close upwards when touched. On repeated touching, the 

 leaflets of the neighbouring pinnae also close together, and the fact that 

 when the touch is given to one of the pinna? the movement is conveyed to 

 the others, until at last the entire leaf sinks down and hangs as if withered, 

 points to the power of transmitting impulse ; after a short time the leaf- 

 stalk rises and the leaf expands again. It is noteworthy that a touch on 

 the upper side of the leaf has no effect. This appears to be an analogous 

 trait to that which is found in many insects, and, in fact, in all parts of the 

 animal kingdom, of feigning death at anyone's approach or when slightly 

 touched. 



The Mimosa, too, goes to sleep when night comes on ; even a cloud 

 passing over the sun will cause its leaves to fold up and sink down ; 

 in fact the whole plant appears to go to sleep. In going to sleep the 

 Mimosa is not, however, at all singular, as most species of plants close 

 their leaves and flowers at night. On the other hand, there are some 

 which, like the beasts of the forest, hail the setting sun as a signal for 

 activity. This sleep of plants, which without doubt is physiologically the 

 same as animal sleep, does not exist without a reason. The act of sleep- 

 ing is, in the higher animals, symptomatic of repose in the brain and 



