INTRODUCTION. 



19 



Differences of this kind, between organized beings, are what are termed varieties. 



There is no proof that all the differences which now distinguish organized beings are 

 such as may have been produced by circumstances. All that has been advanced upon 

 this subject is hypothetical: experience seems to show, on the contrary, that, in 

 the actual state of things, varieties are confined within rather narrow limits ; and, 

 so far as we can retrace antiquity, we perceive that these limits were the same as at 

 present. 



We are then obliged to admit of certain forms, which, since the origin of things, 

 have been perpetuated without exceeding these limits ; and all the beings appertaining 

 to one of these forms constitute what is termed a species. Varieties are accidental 

 subdivisions of species. 



Generation being the only means of ascertaining the limits to which varieties may 

 extend, species should be defined the reunion of individuals descended one from the 

 other, or from conwwn parents, or from such as resemJjle them as closely as they 

 resemble each other ; but, although this definition is rigorous, it will be seen that its 

 application to particular individuals may be very difficult when the necessary experi- 

 ments have not been made/"^ 



To recapitulate, — absoq^tion, assimilation, exhalation, developement, and generation, 

 are the functions common to all living beings ; birth and death, the universal limits of 

 their existence ; a porous, contractile tissue, containing within its laminae liquids or 

 gases in motion, the general essence of their structure ; substances almost all 

 susceptible of being converted into liquids or gases, and combinations capable of easy 

 transformation into one another, the basis of their chemical composition. Fixed 

 forms, and which are perpetuated by generation, distinguish their species, determine 

 the complication of the secondary functions proper to each of them, and assign to them 

 the office they have to fulfil in the grand scheme of the universe. These forms 

 neither produce nor change themselves ; the life supposes their existence ; it can exist 

 only in organizations already prepared ; and the most profound meditations, assisted 

 by the most delicate observations, can penetrate no further than the mystery of the 

 pre-existence of germs. 



DIVISION OF ORGANIZED BEINGS INTO ANIMALS AND VEGETABLES. 



Living or organized beings have been subdivided, from the earliest times, into ani- 

 mate beings, or those possessing sense and motion, and inanimate beings, which enjoy 



• TTint insurmountable difficulties oppose tlic rifiid determination of 

 species, and, consequently, render even the definition of the term 

 impossible, except in a very vague and loose manner, will readily 

 appear on consideration of some of the phenomena presented. 

 The prevalent idea is, that a ipecies consists of the a(,'gregate of 

 individuals descended from one original parentage, wliich alone are 

 supposed to be cnppible of producing olTspring that are prolific inter 

 se ; and that when individuals, not of the same pristine derivation, 

 Interbreed, the hybrids are necessarily inulrs, which are either quite 

 sterile, or at most can only propagate with individuals ol unmixed 

 descent. But it so happens, that every possible grade of approxi- 

 mation is manifested, from the most diverse races, to those which are 

 utterly undiatinguishable ; while, even in the latter case, urgent ana- 

 logies, notnTllist^nding, sometimes forcibly indicate a separateness of 

 origin ; as when a series of analogous races inhabiting distant regions 

 arc compared togetlier, some of which are obviously difTerent, others 

 doubtfully 30, aud some apparently identical. And it remains in ht; 

 shown whether such intimately allied races as some of thesQ, pvcu if 

 not descended from a cumjoon stock, (wliich of course cannot be 



iccrtained), would not ji 

 :rpetuating the mingle 

 ;ainst this contingency, 

 ost naturalists would co 

 er dissimilar, as varic 



iducc hybrids capable of transmittinj; 

 breed, it is true that Cuvier gi. 

 1 the wording of his definition ; and 

 :iir in regarding such miseible races, 

 ely of the i 



arises, whether there be not rfijf^reni deg^fes of fertility in hybrids, 

 corresponding to the amount of ajfinitt/, or physiological aceordancj, 

 subsisting betwixt the parent races ; it being only within a certaiu 

 sphere of that affinity that they can he produced at all ; besides whieh, 

 as hybrids arc seldom exactly intermediate, and in some instances 

 (particularly among mutHparoua races) have been known to resemble 

 entirely one or the otb.ijr parent, it may be presumed that this circum- 

 stance would also materially affect their capability of propagation. 

 E.^perimoots arc needed to solve this important problem, though there 

 is every reason to suspect that the following proposition will evcnlu- 

 allv gain the general assent of naturalists., viz., that lehile tansiderable 

 diisitiiilariti/ does not of vcessitt/ hnph/ specJJicat divcriity, the con- 

 vene eguiitly holds., that absolute raemblance faih of ittelf to con 

 stiluCc spccijicat iVeiiiijIy,— En. 



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