INTRODUCTION. v 



burning feathers; and they give out that smell the more strongly, the less proportion 

 the lime which remains bears to the whole substance. Only a few aquatic plants con- 

 tain lime, while several of them contain silex, but that is in the bark, rather than the inner 

 parts ; as, in those animals which contain it, it is in the case rather than the animal itself. 

 Burn a bit of sponge or of coralline, and then a bit of the sea-weed or other vegetable 

 which resembles it the most, and the smell will at once point out which is the animal sub- 

 stance, and which the vegetable. 



It is not by any essential difference in the matter of which they are composed, that we 

 are enabled to ascertain to which of the three kingdoms of nature any substance belongs, for 

 all matter, considered in its mechanical and chemical properties only, is mineral, even when 

 it forms part"of the organisation or structure of a vegetable or of an animal. The kingdom 

 must be determined from the combination and arrangement of the parts. If these are every- 

 where the same, and the whole dependent upon those general laws of mechanics and 

 chemistry, which hold in like manner, though not to like extent, between particle and 

 particle, as between mass and mass, so that the larger mass may be considered merely as a 

 multiple of the smaller, then the substance is a mineral one ; and it is a solid, a liquid, or an 

 air, or gas, according to the state, which state depends upon the great modifying principle, 

 or principle of action, in matter, which we know only in its effects, and which we call 

 magnetism, electricity, light, heat, vegetable life, animal life, according as it appears in 

 different modifications, rather than from any knowledge that we have of it in itself, either 

 as essentially the same, or essentially different, in those several modifications, and the almost 

 endless diversities in which they appear in nature, or in the operations of art. 



When the parts of a subject, whether formed of the same combination of matter, or of 

 different ones, have a local distribution, and a difference of function, so that the whole 

 subject is not a multiple of any one of them, but the aggregate of the whole, and has its 

 properties as a compound being, depending upon the form and arrangement of those parts, 

 rather than upon their mere chemical or mechanical properties as matter, then we call it an 

 organic or organised being, the production, not of the common principles of chemical and 

 mechanical action, but of life : which life, in fact, acts in opposition to the common laws of 

 mechanics and chemistry ; and when from any cause it can so act no longer, the organic 

 being dies, ceases to display any of the functions of organic life, and becomes an organic 

 remain; and though, as such, some parts of it, as for instance, the bones and shells 

 are found, not merely in accumulations of mud and rubbish in a loose state but after they 

 have been consolidated into rocks, there are always some parts of the organic structure which 

 yield to the common laws of matter so soon after the life is extinct that we can have no 

 interval of time between them. The hard timber of the oak or the cypress may remain for 

 centuries; but the sapwood, and especially the living body, intermediate between the 

 bark and the wood, speedily perishes. The bones take some time to moulder in the earth, 

 and they remain even longer bleaching upon its surface, especially if the climate is uniformly 

 cold ; but the most anxious watchfulness can hardly determine whether the breath in the 

 nostril, or the beam of life in the eye, is the first to vanish. 



The distinctions of the three kingdoms of nature are thus not absolute and essential, 

 but relative. The matter which is now in one of them may have formerly been in another ; 

 and may be in another again. But the relative difference is generally obvious enough ; and 

 we can not only, in most instances, easily draw the line between what is living and what is 

 not, but in dead matter we can distinguish the organic remain from that which either never 

 has been organised, or has so far yielded to the laws of inorganic matter as to have had all 

 its organic characters ; and of organic substances, whether living or dead, we can generally 

 distinguish between the animal and the vegetable. 



