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Show 8 INTRODUCTION • second kind of change that appears to be the cause of natural death. . 1 1 If we examine the various living bodies mo~e c ose y, ~e find they possess a common .structur~, which a httle reflection soon causes us to Perce·ive 1s essential to a vortex such as the vital motion. . Solids, it is plain, are necessary to these bodies, fo: the maintenance of their forms; and fluids for the _conservatiOn of motion in them. Their tissue, accordingl!,, 1s c?m1'osed of network and plates, or of fibres and solid lammre, w1thi? whose interstices are contained the :fluids; it is in these fi~Ids that the motion is most continued and extended. Foreign. s~b~ stances penetrate the body and unite. with them; they nourish the solids by the interposition of their molecules, and also detach from them those that are superfluous.. It is in a liquid or gaseous form that the mat~ers to be ~x.~aled tra;erse ~he pores of the living body ; but In return, 1~ IS the sohd~ which contain the :fluids, and by their contractiOn commumcate to them part of their motion. . . . . This mutual action of the :fluids and sohds, this transitiOn of molecules, required considerable affinity. in their ~hemical composition • and such is the fact-the sohds of orgamzed bodies being n:ostly composed of elements easily convertible into :fluids or gases. The motion of the fluids needing also a constantly repeated action on the part of the solids, and communicating one tO' them required in the latter both :flexibility and dilatability; and :ccordingly we find this character nearly general in aU organized solids.. . This structure common to all living bodies; this areolar tis· sue ' whose more ~r less :flexible fibres or laminre intercept fluid.s · more or less abundant; constitutes what is called the or gam· zation. As a consequence of what we have said, it follows, that life can be enjoyed by organized bodies only·· Organization, then, results from a great variety of arrange· ments, which are all conditions of life ; and it is easy to con· ceive, that if its effect be to alter either of these conditions, so INTRODUCTION. 9 as to arrest even one of the partial motions of which it is composed, the general movement of life must cease. Every organized body, independently of the qualities common to its tissue, has a form peculiar to itself, not merely general and external, but extending to the detail of the structure of each of its parts; and it is upon this form, which determines the particular direction of each of the partial movements that take place in it, that depends the complication of the general movement of its life---it constitutes its species and renders it what it is. Each part co-operates in this general movement by a peculiar action, and experiences trom it particular effects, so that in every being life is a. whole, resulting from the mutual action and re-action of all its parts. Life, then, in general, pre-supposes orga.nization in general, and the life proper to each individual being pre-supposes an organization peculiar to that being, just as the movement of a clock pre-supposes the clock; and accordingly we behold life only in beings that are organized and formed to enjoy it, and all the efforts of philosophy have never been able to discover matter in the act of organization, neither per se, nor by any external cause. In fact, life exercising upon the elements which at every moment form part of the living body, and upon those which it attracts to it, an action contrary to that which, without it, would be produced by the usual chemical affinities, it seems impossible that it can be produced by these affinities, and yet we know of no other power in nature· capable of re-uniting previously separated molecules. The birth of organized beings is, therefore, the greatest mystery of the organic economy and of all na:ture : we see them developed, but never being formed; nay more, ill those whose origin we can trace, have at first been attached to a body similar in form to their own, but which. was developed before them-in a word, to a parent. So lorig as the offspring has no independent existence, but participates in that of its parent, it is called a germ. The place to which the germ is attached, and the cause which deta:ches it and gives it an independent life, vary; but V~I~B . |