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Show 6 INTRODUCTION. racters, which is itself derived from that of the conditions of existence. The parts of a being possessing a mutual adaptation, some traits of character exclude others, while on the contrary, there are others that require them. When, therefore, we perceive such or such traits in a being, we can calculate before hand those that co-exist in it, or those that are incompatible with them. The parts, the properties, or the traits of conformation, which have the greatest number of these relations ofincompatibility or of co-existence with others, or, in other words, that exercise the most marked influence upon the whole of the being, are called the important characters, dominating characters; the others are the subordinate characters, all varying in degree. This influence of characters is sometimes determined rationally, by the consideration of the nature of the organ. When this is impracticable, we have recourse to simple observation; and a sure mark by which we may recognise the important characters, and one which is drawn from their own nature, is their superior constancy, and that in a long series of different beings, approximated according to their degrees of similitude, these characters are the last to vary. That they should be preferred for distinguishing the great divisions, and that in proportion as we descend to the inferior subdivisions, we can also descend to subordinate and variable characters, is a rule resulting equally from their influence and constancy. There can be but one perfect method, which is the natural method. We thus name an arrangement in which beings of the same genus are placed nearer to each other than to those of the other genera; the genera of the same order nearer than those of the other orders, &c. &c. This method is the ideal to which natural history should tend; for it is evident that if we can reach it, we shall have the exact and complete expression of all nature. In fact, each being is determined by its resem· blance to others, and difference from them; and all these rela· tions would be fully given by the arrangement in question. In a word, the natural method would be the whole science, and every step towards it tends to advance the science to per· fection. INTRODUCTION. 7 . Life being t~e most important of all the properties of be~ ngs, ~nd the highest of all characters, it is not surprising that I~ ha~ In all ages been made the most general principle of dis~ mction;. and that ~a~~ral beings have always been separated mto two Immense diVISions, the living and the inanimate . ' Of Living Beings, and Organization in general. If~ in o~d~r to obtain a correct idea of the essence of life, we ~onsider It In. those beings in which its effects are the most Simple, we qm~kly perceive that it consists in the faculty poss~ ssed by certam corporeal combinations, of continuing for a ~1me an~ under ~ ~eterminate form, by constantly attracting mto their composition a part of surrounding substances and ren d erm. g to the elements, portions of their own. ' _Life then is a vortex, more or less rapid, more or less comphc~ ted, the direction of which is invariable, and which always c~rries along molecules of similar kinds, but into which indiVIdual ~olecules are continually entering, and from which they are continually departing; so that the form of a living body is more essential to it than its matter. As long as this motion subsists, the body in which it takes place is living-it lives. When it finally ceases, it dies. Aft~r death, the elements which compose it, abandoned to the ordinary chemical affinities, soon separate, from which more or less quickly, results the dissolution of the once livin; body. It was then by the vital motion that its dissolution was ar.,.est-ed ' an d. I· ~ e1 e m~nts were held I· n a temporary union. ~ I' ~n. hvmg bodies die after a certain period, whose extreme Imit Is fixed for each species, and death appears to be a ne~ essary consequence of life, which, by its own action, insensiJy alters the structure of the body, so as to render its continuance impossible. In fact, the living body undergoes gradual but continual ~hanges, during the whole term of its existenc~. At first it rm cr.e as es I· n d I· mensi·O ns, accord·m g to proportions, and with' in Imits, :fixed for each species and for each one of its parts· it then augm en ts m· d ens·i ty ·m the most of its parts :-it is t'h is |