62 



ESSAY ON CLASSIFICATION. 



Part I. 



such different relations to the peciihar kind of blood of the Articidata,^ that no 

 homology can be traced Ijetween them and the lungs of Vertebrata, no more 

 than between the so-called lungs of the air breathing MoUusks, whose aei'ial respira- 

 toiy cavity is only a modification of the peculiar kind of gills observed in other 

 MoUusks. Examples might easily be multiplied ; I will, however, only allude further 

 to the alimentary canal of Insects and Crustacea, with its glandular appendages, 

 formed in such a different way from that of Vertebrata, or MoUusks, or Radiata, to 

 their legs and wings, etc., etc. I might allude also to what has been called the foot 

 in MoUusks, did it not appear like jjretending to suppose that any one entertains 

 still an idea that such a name implies any sunUarity between their locomotive 

 apparatus and that of Vertebrata or Articulata, and yet, the very use of such a 

 name misleads the student, and even some of the coryphees of our science have 

 not freed themselves of such and similar extravagant comparisons, especiaUy with 

 reference to the sohd parts of the frame of the lower animals.^ 



The identification of functions and organs was a natural consequence of the 

 prevaUing ideas respecting the influence physical agents were supposed to have upon 

 organized beings. But as soon as it is understood, how difterent the organs may 

 be, which in animals perform the same function, organization is at once brought into 

 such a position to physical agents as makes it utterly impossible to maintain any 

 genetic connection between them. A fish, a crab, a mussel, living in the same 

 waters, breathing at the same source, should have the same respiratory organs, if the 

 elements in which these animals live had any thing to do with shaping their organi- 

 zation. I suppose no one can be so shortrsighted, as to assume that the same 

 physical agents acting upon animals of different types, must produce, in each, peculiar 

 organs, and not to perceive that such an assumption implies the very existence of 

 these animals, independently of the ply^sical agents. But this mistake recurs so 

 constantly in discussions upon this and simUar topics, that, trivial as it is, it requires 

 to be rebuked.'^ On the contrary, Avhen acknowledging an intellectual conception, 



niden, in Siebold und KoLLHiER's Zeitschrift, f. 

 wiss. Zool., 1849, I., p. 246. 



* Blanciiard, (Em.,) De la circulation dans les 

 Insectes, Compt, Rend., 1847, vol. 24, p. 870. — 

 Agassiz, (L.,) On the Circulation of the Fluids in 

 Insects, Proc. Amer. Asso., for 1849, p. 140. 



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

 Knocheu- und Schalengeriistes, Leipzig, 1828, 1 vol., 

 foL, p. 61-89. 



' I hope the day is not far distant, when zoolo- 

 gists and botanists will equally disclaim having 



shared in the physical doctrines more or less pre- 

 vailing now, respecting the origin and existence of 

 organized beings. Should the time come when my 

 present efforts may appear like fighting against 

 windmills, I shall not regret having spent so much 

 labor in urging my fellow-laborers in a right direc- 

 tion ; but at the same time, I must protest now 

 and for ever, against the bigotry spreading in some 

 quarters, which would press upon science, doctrines 

 not immediately flowing from scientific premises, 

 and check its free progress. 



