22 -^n Introduction to Zoology. 



observations, the reunion or distribution of which with reference to their 

 relations constitutes a system, and the more numerous the facts observed, 

 the more natural their arrangement, and the more simple and rational the 

 deductions from them, the nearer to perfection must that system be. 

 Classification then depends upon comparison, that is, upon the discovery 

 of similarities and dissimilarities between difierent individuals composing 

 the animal kingdom, and the arranging these accordingly, first, in groupes, 

 then the uniting under a more general term such of these groupes as are 

 most resemblant, and thus abstracting still further at each step, to place 

 the whole under a regular methodical arrangement. 



Now since the basis upon which the whole of such an arrangement rests, 

 consists purely in certain points of difference and analogy really existing 

 in nature between the ultimate groupes, and since the proximate abstrac- 

 tions are all strictly and obviously deduced from them, such an arrange- 

 ment deserves the term of " natural." It was never invented, it was 

 discovered, and it rests upon a basis so secure, that however imperfect the 

 present state of our knowledge may be, or however numerous and import- 

 ant the observations hereafter to be made, still the general principles upon 

 which it rests can never be subverted. 



It is found, by a careful collation and comparison of observed facts, that 

 the co-ordinate members which compose each individual, as well as those 

 composing the whole animal series, are formed with reference to particular 

 purposes; and that in all cases a particular organisation so invariably 

 accompanies particular iiabitudes, that they readily admit of deduction the 

 one from the other : and it is also found that in all the numerous and varied 

 contrivances which are met with, both in the invertehrated, and more 

 obviously in the vertebrated animals, there is a remarkable adherence to 

 certain types or patterns necessarily manifested, all the varieties being 

 modifications of parts rather than alterations of the whole. 



It is a great, though perhaps a common error, to suppose, that in the 

 existing state of our knowledge, " a regular series of beings can be traced 

 up from the lo\vest monad to man, through a great variety of almost in- 

 sensible gradations." If this be really the case, there is at least nothing 

 known at present by which it can be exhibited. It is indeed perfectly true 

 that very many links of such a chain do exist, and that with reference to 

 them is determined the relative importance and position of those groupes, 

 whose characteristics had been previously determined; but there appear 

 to be so many breaks, and so many duplicate links, that even with the aid 

 of extinct and fossil animals, nothing like an imperceptible gradation has 

 been hitherto traced. 



There is probably no organised being, as Cuvier has observed, of a 

 simple character, all being compounded of certain traits of conformation ; 

 and if we wish to distinguish any one being from another, it can only be 

 by collecting all these individual traits, and deciding which of them arc 



