654- 



SKELETON. 



are proper to the plus original. This interpre- 

 tation will, I believe, stand the test of rigor- 

 ous reasoning, and will teach the anatomist 

 this, or nothing truthfully besides this, viz. 

 that if the presential characters of the fore- 

 limbs manifest such a diversified condition 

 as precludes him from naming them quan- 

 titatively equal and uniform things, still the 

 diversity, such as we find it, can have occurred 

 by no other process or law, save that of de- 

 gradation or the metamorphosis of elemental 

 parts. A certain part is wanting to one 

 organ compared with another organ ; and if 

 it be by reason of the want of this part in one 

 organ, which part is present in another, that I 

 am unable to name both these organs uniform, 

 it is no less true that this very want of the 

 part constitutes the species. 



The fore-limbs of the man, the horse, the 

 ruminant, the carnivore, the rodent, the mar- 

 supial animal, the bird, the reptile, are not 

 quantitatively uniform things, and this is the 

 only reason why they are various things. If 

 it be this quantitative difference which in- 

 duces us to classify them separately, it is only 

 this same mode of difference which stands hi 

 our way preventing us from naming them ab- 

 solutely alike. The one organ has one part 

 which the other organ has not, and therefore 

 both organs are various or special ; but it is 

 still most true, that it is the want of the known 

 part rather than the superaddition of an un- 

 known part which constitutes both organs 

 thus special. 



The special thing compared with the ideal 

 unity is simply the minus quantity compared 

 with the plus quantity. All comparative 

 method proves this. When I compare the 

 fore-limb of the ass with the arm of the man, 

 and endeavour to ascertain the law which has 

 rendered the first as a form special to the 

 last, I find that my analysing instrument must 

 be not the scalpel but the calculation. For 

 while I see that in the soliped member are 

 arranged certain parts taking order in the 

 self-same manner as the like parts in the 

 human arm ; and while I further discover that 

 the latter organ developes certain parts, 

 which parts are not developed for the former, 

 and that hence only arises the difference or 

 species ; I must therefore conclude that the 

 species depends upon the absence of some- 

 thing, which thing, being absent, I cannot dis- 

 sect by any other instrument than the under- 

 standing ; and the thing, though absent, may- 

 be still visible to the mental although in- 

 visible to the physical eye. 



For the knowledge of the thing absent, 

 viz. some of the digits of K,fig. 483., is, I con- 

 tend, equal to the knowledge derivable from 

 the actual presence of the very same quan- 

 tity, viz. those digits in A ; and, therefore, so 

 long as I know the quantity which is absent 

 from one ens to be the same as the quantity 

 which is present to another ens, this must 

 furnish me with the idea of equality, or the 

 uniformity, as saliently as if the quantity were 

 present for both enses. When, for example, 

 I compare the soliped or the cloven foot 



with the human hand, I find that the lesser 

 ens is contained in the greater ens, and that 

 the other parts, which are wanting to the 

 lesser, are still manifest in the greater; there- 

 fore I conclude, that as the greater, viz. the 

 human hand, can undergo a metamorphosis 

 or subtraction of parts, so as to reduce it to 

 the proportions of the cloven or the soliped 

 organ successively, so has the original or plus 

 quantity, which may be regarded as equal to 

 the human hand, undergone a metamorphosis 

 of parts in such degree as now yields for our 

 contemplation the special or minus quantities, 

 which we name cloven or soliped foot. 



PROP. XLI. The scapulary and pelvic mem- 

 bers are homologous. In a former place I 

 have given reasons why we should consider 

 the clavicles, the pubic, and ischiadic bones 

 as the hornologues of ribs; and therefore I 

 shall not need their presence in this place 

 while holding comparison between the fore 

 and hind members.* 



The fore-limb (Jig. 485. A.) separated from 

 the clavicle, consists, like the hind limb (E), 

 separated from the pubisand ischium,ofafixed 

 and invariable number of segments ; and the 

 parts which constitute these segments in both 

 are absolutely corresponding. The scapula 

 (A) corresponds to the ilium (E) ; the hu- 

 merus (B) to the femur (F) ; the radius (n) 

 to the tibia (n) ; the ulna ( c) to the fibula (G). 

 The hand is manifestly the counterpart of the 

 foot. The carpus represents the tarsus ; the 

 metacarpus corresponds to the metatarsus ; 

 the phalanges of the hand are represented in 

 the phalanges of the foot. The pisiform bone 

 (r/) of the carpus is similar to the os calcis (Y/) 

 of the tarsus ; the great toe represents the 

 thumb ; the little toe simulates the little 

 finger. The common structural identity be- 

 tween both organs is plainly manifest at all 

 points save one ; and this, though often at- 

 tempted to be explained, has not as yet 

 yielded up its mystery. How happens it 

 that the patella (/<) and fore aspect of the 

 hind limb (E), corresponds to the olecranou 

 (A) and back of the fore-limb (A)? I believe that 

 the complete solution of this problem may be 

 had from the following remarks made in 

 reference to Jig. 485. 



On comparing the right scapulary organ 

 (A, B, c, D) with the left pelvic member 

 (E, F, G, H), I find that the fore aspect of the 

 former does not correspond to the fore aspect 

 of the latter ; but when I compare the back 

 of the arm A, B*, c*, D* with the front of the 

 lower member (E, F, G, H), their correspond- 



* Vicq d'Azyr regarded the coracoid and acromion 

 processes of the scapula as representing the pubic 

 and ischiadic, bones, while Cruveilhier states it as 

 his opinion that the spine and acromion process of 

 the scapula has no part analogous to them in the 

 ilium. Professor Owen considers the clavicle as the 

 homologue of the os pubis, agreeing in this view 

 with Cruveilhier. But, according to Professor 

 Owen's views, it is not with the rib that either the 

 clavicle os pubis or ischium manifests an homology ; 

 on the contrary, he regards the iliac bone and the 

 scapula as the true representatives of the ribs his 

 pleurapophysiaJ elements. 



