PHY 



OR, BOTANICAL DICTIONARY. 



PHY 



295 



tica Hierochuntica, commonly called the Rose of Jericho, the 

 seed-vessels of the genus Mesemhryanthemum, many species 

 of which are known to gardeners by the name of the Candian 

 Flower, the dry calix of Carlina vulgaris, are in this respect 

 the same as wood. They expand in wet weather, and con- 

 tract when dry. The same observation applies to Liver- 

 worts 'and Mosses, which during summer appear to be 

 withered, but in cool moist weather, and in autumn, again 

 begin to grow and expand. The contractility of ligneous 

 fibres fits them for being Hygrometers. Formerly it was 

 thought that plants could grow in breadth, only by the ex- 

 pansion of the interstices between the fibres of the wood 

 when moisture pervades them. Mr. De Luc, however, has 

 shown, that the fibres themselves may be elongated, though 

 in a small degree, and may again contract. And he has 

 made the singular remark, that box-wood contracts its fibres 

 longitudinally when moist, but elongates them in a dry at- 

 mosphere. It however undergoes the changes in breadth 

 iu the same manner as other wood. He examined a great 

 number of different sorts of wood ; but not one showed the 

 .phenomenon of box-wood. That vegetables as organized 

 bodies are possessed also of vital powers, admits of no doubt, 

 as is sufficiently demonstrated by their growth, formation, 

 and decay. On a few different parts only, the operation of 

 the applied stimulus becomes visible. The leaves of Mimosa 

 pudica, sensitiva, casta, of Oxalis sensitiva, Dioneea musci- 

 pula, and otricr plants which grow only within the tropics 

 and under the equator, contract when touched. Less con- 

 spicuous, but easily demonstrable, is the contractility in the 

 indigenous species of Sun-dew, Droscra rotundifolia and 

 longifolia. 1 he filaments of Urtica, Parietaria, Berberis, and 

 others, show great irritability, and likewise the pistils of some 

 plants, especially the stigma of Martynia. According to some 

 experiments, light acts as a particular stimulus upon plants. 

 Vegetables appear to be little susceptible of the power of 

 Galvanism. The result of the experiments hitherto made, 

 is so very dubious that we cannot venture to advance any 

 opinion upon this subject. Electricity acts powerfully upon 

 plants as well as upon animals, and the effects which it pro- 

 duces in both are exactly the same : viz. Electricity, when 

 faintly applied, is beneficial to their growth, but becomes 

 hurtful to them when exerted with any degree of violence. 

 Van Marum destroyed plants by violent electric shocks, and 

 I myself made a similar experiment on the Drosero rotundi- 

 folia. This plant remained quite uninjured in the electrical 

 bath, but when I began to extract sparks from its leaves, it 

 soon withered away. The power of reproduction, which is 

 one of the consequences of life, is common to animals and 

 plants. It is less perceptible in plants than in animals and 

 worms. Slight wounds in the cortex heal very easily ; and 

 Duhamel, after he had, with the greatest care, completely 

 removed the bark of a tree, observed it again beginning to 

 appear. With regard to plants of many stamina, it has been 

 alleged by some, that, immediately after the removal of the 

 stamina, similar bodies, though void of pollen, are repro- 

 duced. But this is not properly reproduction, because the 

 parts thus procreated are not of the same structure as for- 

 merly. The leaf of a plant, which has been at all mutilated, 

 will never be renewed, neither will the leaves of flowers, 

 which have been injured, either in a perfect or imperfect 

 state, ever be fully reproduced. If we divest a willow, or 

 any other tree, of its branches, and the tree produce new 

 ones, we cannot look upon this as a reproduction, because 

 the tree is a compound plant, and every branch, or rather 

 every bud, can be considered only as a particular plant. 

 Thus, then, the growth of the pruned branches is a produc- 

 90. 



Uon, but not a reproduction, for in the greater part of leaf- 

 bearing wood, the whole surface is capable of producing 

 buds and branches. Philosophers have constantly endea- 

 voured to discover resemblances between animals and plants. 

 Aristotle called vegetables reversed animals. Linneus pur- 

 sued this idea still farther; but his lively imagination carried 

 him too far, when he denominated heat, the heart, and 

 earth, the stomach of plants, and even when he, with more 

 justice, compared the leaves of plants to the lungs of ani- 

 mals. Comparisons of this kind must always fail, as ani 

 mals and plants differ very materially in the form of the 

 organs of which they are composed. 



" But the most successful on this head was the immortal 

 Bonnet, who, in a very ingenious manner, has compared the 

 egg, the embryo, the nourishment, and the generative organs 

 of animals, to those of vegetables. This likeness, which phi- 



losophers observed between animals and plants, chiefly con- 

 sisted in. properties, which organized bodies possess without 

 respect to their structure. It is, therefore, certainly worth 

 while, to consider more accurately, in what respects plants 

 differ from animals. Animals take food by a certain aper- 

 ture, and have a particular canal by which they propel their 

 excrementitious matter. Plants, on the other hand, take in 

 nourishment with their whole surface, and except transpira- 

 tion, which they possess in common with animals, have no 

 peculiar canal to expel their excrements, unless we consider 

 the drops which are found on the roots of some luxuriant 

 plants as a proof of the contrary. Plants have a structure 

 altogether different from that of animals. They consist of 

 variously combined vessels, which are surrounded by a cel- 

 lular membrane. The existence of muscles in plants has not 

 yet been clearly evinced, nor have nerves hitherto been per- 

 ceived in them. The wood, which some have compared to 

 bones, has certainly not the least resemblance to them. 

 Plants consist of a cuticle, which appears in woody plants 

 to be converted into the outer bark. It covers the inner 

 bark, which is solely composed of vessels. This is followed 

 by the soft wood, as it is called. The wood is enclosed by 

 the last, and surrounds the pith. The inner bark, alburnum, 

 and wood, are one and the same substance at different 

 periods of growth. The inner bark is converted into albur- 

 num, and this into wood. They are all three compressed 

 vessels, which are more or less hard, or still soft. The pith 

 almost entirely disappears in very thick large trunks, by the 

 increasing solidity of the wood, and only in a few plants 

 remains uniformly throughout all parts of the trunk. We 

 find it in herbaceous plants, but most aquatic plants want 

 it entirely. The steins of herbaceous plants have neither 

 alburnum nor wood. The epidermis, which rarely in them 

 is converted into bark, incloses a ring of vessels, correspond- 

 ing with what in woody plants is called the inner bark. 

 Immediately beneath this we have a more or less dense cel- 

 lular membrane, which is often very succulent ; and next in 

 it, a fleshy substance. This incloses the pith, which in fact 

 is a cellular texture of a different nature, at times dry 

 or juicy, at other times consisting of close and narrow 

 cells. 



" Animals, with the exception of some of the vermes, are 

 simple beings, but most plants not so ; for only some annuals 

 and Palms are simple plants, the rest are all of a compound 

 structure. If we put the seeds of an annual plant in the 

 ground, plants grow from it, which soon flower, produce 

 seeds, and then die. The buds of trees and shrubs are to 

 be considered as annual plants, for as soon as they have 

 blossomed and shed their seeds, they entirely decay. The 

 trunks of trees and shrubs, as well as the roots of perennial 

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