82 ON ORGANIZED BODIES, 



difference ? Both have proceeded from a minute molecule, a nucleus or a 

 germ ; both have a tendency to preserve their derivative or family configura- 

 tion, and. both have been augmented and perfected from one common soil. 

 If I break the stone to pieces, every individual fragment will be found pos- 

 sessed of the characteristic powers of the aggregate mass ; it is only altered 

 in its shape and magnitude : but if I tear off a branch from the plant, the 

 branch will instantly wither, and lose the specific properties of the parent 

 stock. 



No external examination, or reasoning d priori will explain this difference 

 of effect. It is only by a minute attention to the relative histories, interior 

 structures, and modes of growth of the two substances, that we are enabled 

 to offer any thing like a satisfactory answer ; and by such examination we 

 find that the stone has been produced fortuitously, has grown by external 

 accreuon, and can only be destroyed by mechanical or chemical force; while 

 the plant has been produced by generation, has grown by nutrition, and been 

 destroyed by death : that it has been actuated by an internal power, and pos- 

 sessed of parts mutually dependent and contributory to each other's functions. 



In what this internal power consists we know not. Differently modified, 

 we meet with it in both plants and animals ; and wherever we find it we de- 

 nominate it the principle of life, and distinguish the individual substance it 

 actuates by the name of an organized being. And hence, all the various 

 bodies in nature arrange themselves under the two divisions of organized 

 and unorganized : the former possessing an origin by generation, growth by 

 nutrition, and a termination by death ; and the latter a fortuitous origin, ex- 

 ternal growth, and a termination by chemical or mechanical force. 



This distinction is clear, and it forms a boundary that does not seem to be 

 broken in upon by a single exception. In what, indeed, that wonderful power 

 of crystallization consists, or by what means it operates, which gives a definite 

 and geometrical figure to the nucleus or primary molecule of every distinct 

 species of crystal; and which, with an accuracy that laughs at all human 

 precision, continues to impress the same figure upon the growing crystal 

 through every stage of its enlargement, thus naturally separating one spe- 

 cies from another, and enabling us to discriminate each by its geometrical 

 shape alone we know not : but even here, where we meet with an approach 

 towards that formative effort, that internal action and consent of parts which 

 peculiarly characterize the living substance, there is not the smallest trace 

 of an organized arrangement ; while the origin is clearly fortuitous, and the 

 growth altogether external, from the mere apposition of surrounding matter. 



So, on the other hand, in corals, sponges, and fuci, which form the lowest 

 natural orders among animals and vegetables, and the first of which seems 

 to constitute the link -that connects the animal and vegetable with the mineral 

 world, for it has in different periods been ascribed to each, simple as is their 

 structure, and obtuse as is the living principle that actuates them, we have still 

 sufficient marks of an organized make ; of an origin by generation, the gene- 

 ration of buds or bulbs, of growth by nutrition, and of termination by death. 



But the animal world differs from the vegetable as widely as both these 

 differ from the mineral. How are we to distinguish the organization of ani- 

 mals from that of plants ? In what does their difference consist ] and here 

 I am obliged to confess, that the boundary is by no means so clearly marked 

 out ; and that we are for the most part compelled to characterize the differ- 

 ence rather by description than by definition. Nothing, indeed, is easier 

 than to distinguish animals and vegetables in their more perfect states : we 

 can make no mistake between a horse and a horse-chestnut tree, a butterfly 

 and a blade of grass. We behold the plant confined to a particular spot, 

 deriving the whole of its nutriment from such spot, and affording no mark 

 either of consciousness or sensation ; we behold the animal, on the contrary, 

 capable of moving at pleasure from one place to another, and exhibiting not 

 only marks of consciousness and sensation, but often of a very high degree 

 of intelligence as well. Yet, if we hence lay down consciousness or sen- 

 sation, and locomotion, as the two characteristic features of animal life, we 



