244 ANATOMY OF VERTEBRATES. 



logies, under all tlie various modifications by wliich they are 

 adapted to the several modes and spheres and grades of existence 

 of the different species — should be the great aim of anatomical 

 science ; as l^eing that which reduces its facts to the most natural 

 order, and their exposition to the simplest expressions. 



It is impossible, in pursuing the requisite comparison upward 

 through the higher organised classes, not to recognise resemblances 

 between the idtimate states and forms of ichthyic organs, and the 

 transitory condition of the same parts, in the higher species. 

 But these resemblances have been sometimes overstated, or pre- 

 sented under unqualified metaphorical expressions, calculated to 

 mislead the student and to obstruct the attainment of complete 

 conceptions of their nature. We should lose most valuable fruits 

 of anatomical study were vfe to limit the application of its facts 

 to the elucidation of the unity of the verteljrate type of organi- 

 sation, or if wc were to rest satisfied with the detection of the 

 analogies between the embryos of higher and the adults of lower 

 species in the scale of being. We must go further, and in a 

 different direction, to gain a view of the fruitful jihysiological 

 principle of the relation of each adaptation to its appropriate 

 i'unction, if we would avoid the danger of resting in sjieculations 

 on the mode of operation of derivative secondary causes, and of 

 blinding the mental vision to the manifestations of Design which 

 the various forms of the Animal Creation oft'er to our contem- 

 plation. 



To revert, then, to the skeleton of Fishes, with a view to the 

 teleological application of the facts determined by the studv of 

 this complex modification of the animal framework. Xo doubt 

 there is analogy between the cartilaginous state of the cndo- 

 skeleton of Cuvier's Chondropterygians, and that of the same 

 part in the emlnyos of air-lireathing Vertelirates ; Init why the 

 gristly skeleton should be, as it connnonly has been pronounced to 

 be, absolutely or teleologically inferior to the bouv one is not so 

 obvious. The ordinary course of age, decrepitude, aud decav of 

 the living body is associated witli a ])rogressivc accumulation of 

 earthy and inorganic ])articles, gradually ini])cding and stiffeniu"- 

 the movements, and finally stopping the i)lay of tlic vital machine. 

 And I know not why a flexible vascular animal substance should 

 be sujiposed to ))e raised in tlie histological scale because it has 

 become unpregnated, and as it were p^Hrificd, by tlie abundant 

 intus-susception of earthy salts in its areolar tissue." It is iierfcetly 

 intelligible that this accelerated progress to the inori;-anic state 

 may be re()uisile for some special otiice of sucli calcified parts in 



