SENSIBILITY OF PLANTS. 



80 



thirty or forty years, and Kidney-Beans retain their life- 

 principle for a century. Seeds with hard and thick covers, 

 or crusts, generally keep much longer ; while those of 

 fleshy and pulpy fruits are extremely perishable. Dr. 

 Lindley, the great Botanist, raised raspberry plants from 

 seeds which were taken from the stomach of a man, whose 

 skeleton was found thirty feet below the surface of the 

 earth. The body had been buried with some coins of 

 the Emperor Hadrian, and it is probable that the seeds 

 were about seventeen hundred years old. When a deep 

 layer of earth is turned up to the air, seeds which have 

 been buried from times unknown will germinate, and often 

 present entirely different species from any in the neigh- 

 borhood. Within a few years, grains of wheat, obtained 

 from the Egyptian catacombs, where they had lain not 

 less than three thousand years, have been planted in 

 England, germinated, and produced abundantly. 



511. Thus does the ALL-(TOOD, the ALL-WISE, guard 

 the life that he gives, not only by throwing around it in- 

 numerable barriers, but by placing its whole force and 

 power in direct antagonism with Death, so that all its 

 instincts and constitutional tendencies repel decay, and 

 to the last moment resist dissolution. 



CHAPTER XXXI. 



SENSIBILITY OF PLANTS. 



512, CERTAIN motions are observed in plants, which, 

 as they are not to be referred to the operation of any 

 mechanical laws, must be attributed to the existing 

 vitality under the influence of peculiar conditions, or to 

 the presence of a certain sensibility, which plants as 

 well as animals inherit by virtue of their life. But the 

 latter being destitute of muscular fibre, have nothing in 

 common with that property in animals which has been 

 defined as voluntary motion; yet they often exhibit 

 movements which have a certain correspondence with it. 

 These are of two kinds, general and special. The first 

 belong to all plants ; the last only to certain Orders, 

 Tribes, or Individuals. Among the first may be reckon- 

 ed the universal determination of the Root to descend, 

 and of the Stem to ascend in germination, the turning of 

 the upper surface of leaves to the light, and the tendency 

 to exhibit as much of the plant as possible to the influence 

 of that highly vitalizing power, in the position both of 



Seeds with hard crusts ? Raspberries of Dr. Lindley. Wheat from the Cata- 

 combs ? Relate each. What guards of Life ? 



General subject. To what are certain motions to be referred not to bo re- 

 ferred ? Of what animal property are plants destitute ? What do they have 

 corresponding with it? What kinds of sensibility? Define each class, with 



12 



leaves and branches, which evidently seek to expand 

 themselves to the light always, and are especially di 

 rected towards it in obscured situations. Vertical leaves 

 (252) hardly form an exception to this, because their 

 surfaces being alike, they are equally acted on by the 

 light, and their motions are not observed. To the second 

 class may be referred the closing of flowers at particular 

 hours of the day, the folding of both leaves and flowers 

 at night, or in cloudy weather, the many curious move- 

 ments for the dispersion of the seed and pollen, and vari- 

 ous other phenomena which will now be defined. 



513. MOTIONS CAUSED BY LIGHT. The leaves of 

 many plants, and especially those of a pinnate form, as- 

 sume certain positions with the decline of day. These 

 motions, which are exceedingly varied and beautiful, 

 cannot be mechanical, for the leaflets generally bend up- 

 ward, or forward, as in one leaf at Plate XXIX., fig. 5 ; 

 and this, as it may easily be seen, is not a position they 

 would fall into by their own weight. Plants with very 

 delicately winged (279) or ternate (281) leaves, appear 

 more sensible to this influence, such as the White Locust, 

 tree and the Wood-Sorrel, both of which afford fine sub- 

 jects for studying these curious phenomena. The sensi- 

 bility appears to reside in the joint of the leaf-stalk, 

 which is usually bent down in the nocturnal position, the 

 mode of folding being always uniform in any given spe- 

 cies. These habits, collectively, were by Linnaeus poeti- 

 cally denominated the " Sleep of Plants." 



514. PAPILIONACEOUS FLOWERS (403) expand their 

 wings to the air and light in fine weather ; but many of 

 the tribe close their petals at night, and in cloudy wea- 

 ther, some of them receiving additional shelter by the 

 folding over them of their pinnate leaves. The Tamarind 

 tree, which belongs to this family, is thus doubly enfolded 

 by its protecting organs. The Lettuce, Dandelion, and 

 many of the Compositae, have the same habit. Our 

 common White Pond-lily rises and expands with the 

 sun ; but on the approach of night closes its numerous 

 petals and sinks below the surface, to rise and re-expand 

 them on the following morning ; and this it continues to 

 do until the germ is fertilized, and the flowers fall. The 

 celebrated Lotus of Egypt, which is seen at fig. 4, was 

 described by Theophrastus and Pliny as having the same 

 habit, and it is found in the same genus. The Victoria 

 Regia of Guiana, belongs to a nearly allied genus, and is 

 the largest Water Lily known. It is seen at fig. 9 with 



instances. Motions caused by light. What leaves most sensible to its influ- 

 ence how affected at night-fall in what part does the sensibility reside ? 

 Instances. What term applied by Linnaeus ? How are Papilionaceous flowers 

 affected? How the Composits; ? Instances. Habit of the Water-Lilics de- 

 fine. Describe Victoria Regia 



