18 



ESSAY ON CLASSIFICATION. 



Part I. 



SECTION IV. 



LTJITY OF PLAN IN OTHERWISE HIGHLY DIVERSIFIED TYPES. 



Nothing is more striking throughout the animal and vegetable kingdoms than the 

 unity of plan in the structure of the most diversified types. From pole to pole, in 

 every longitude, mammalia, birds, reptiles, and fishes, exhibit one and the same plan 

 of structure,^ involving abstract conceptions of the highest order, far transcending the 

 broadest generalizations of man, for it is only after the most laborious investigations 

 man has arrived at an imperfect understanding of this plan. Other plans, equally 

 wonderful, may be traced in Articulata, in MoUusks, in Kadiata,^ and in the various 

 types of plants,^ and yet this logical connection, these beautiful harmonies,- this infi- 

 nite diversity in iniity are represented by some as the result of forces exhibiting no 

 trace of intelligence, no power of thinking, no faculty of combination, no knowledge 

 of time and space. If there is any thing which places man above all other beings 

 in nature, it is precisely the circumstance that he possesses those noble attributes 

 without which, m their most exalted excellence and perfection, not one of these 



^ AVith reference to this point, consult: Okex, 

 (Lor.,) Ueber die Bedeutung der Scliiidel-Knochen, 

 Frankfort, 1807, 4to. (pamishlet.)— Spix, (J. B.) 

 Cephalogenesis, sive capitis ossei structura, formatio 

 et significatio, Monachii, 181.5, fol. — Geoffroy St. 

 HiLAiRE, (Ex.,) Philosophie anatomique, Paris, 

 1818-1823, 2 vols. 8vo., and several papers in the 

 Annal. des sc. nat., Annal. and Mem. du Museum, 

 etc. — Carus, (C. G.,) Von den Ur-Theilen des 

 Knochen- und Schalengeriistes, Leipzig, 1828, fol. — 

 Owen, (R.) On the Archetype and Homologies of 

 the Vertebrate Skeleton, London, 1848, 8vo. 



^ Oken, (Lor.,) Lehrbuch der Naturphilosophie, 

 Jena, 1809-11, 3 vols. 8vo. ; Engl. Elements of 

 Physio-philosophy, Ray Society, London, 1817, 8vo. 

 — CuviER, (G.,) Sur un nouveau rapprochement a 

 etablir entre les classes qui composent le Regne Ani- 

 mal, Annales du Museum, vol. xix., 1812. — Savi- 

 GNY, (J. C.,) Memoires sur les animaux sans verte- 

 bres, Paris, 1816, 8vo. — Baer, (C. E. v.,) Ueber 

 Entwickelungsgeschichte der Thiere, Konigsberg, 

 1828, 4to. — Leukakdt, (R.,) Ueber die Morphologic 



und die Verwandtschaftsverhaltnisse der wirbcllosen 

 Thiere, Braunschweig, 1848, 8vo. — Agassiz, (L.,) 

 Twelve Lectures on Comparative Embryology, Bos- 

 ton, 1849, 8vo.— On Animal Morphology, Proc. Amer. 

 Assoc, for the Adv. of Science, Boston, 1850, 8vo., p. 

 411. I would call particular attention to this paper, 

 which has immediate reference to the subject of this 

 chapter. — Carus, (V.,) System der thierischen Mor- 

 phologic, Leipzig, 1853, 1 vol. 8vo. 



^ GciTiiE, (J. W.,) Zur Naturwissenhaft iiber- 

 haupt, besonders zur Morphologic, Stuttgardt, 1817- 

 24, 2 vols. 8vo. ; French, Oeuvres d'histoire natu- 

 relle, comprenant divers memoires d'Anatomie com- 

 paree, de Botanique et de Geologic, traduits et an- 

 notes par Ch. Fr. Martins, Paris, 1837, 8vo. ; atlas 

 in fol. — DeCandolle, (A. P.,) Organographie 

 vegetale, Paris, 1827, 2 vols. 8vo. — Bracx, (Al.,) 

 Vergleiehende Untersuchung iiber die Ordnung der 

 Schuppen an den Tannenzapfen, als Einleitung zur 

 Untersuchung der Blattstellung uberhaupt. Act. Nov. 

 Ac. Nat. Curios., vol. xv., 1829. — Das Individuum 

 der Pflanzc, Akad. d. AViss., Berlin, 1853, 4to. 



