484 HISTORY OF PHYSIOLOGY. 



endeavored to fill up the chasm Avhich separates insects from other 

 animals ; and by examining carefully the portions which compose the 

 solid frame-work of insects, and following them through their various 

 transformations in different classes, he conceived that he found 

 relations of position and function, and often of number and form, 

 which might be compared with the relations of the parts of the 

 skeleton in vertebrate animals. He thought that the first segment of 

 an insect, the head, 2 represents one of the three vertebrae which, 

 according to Spix and others, compose the vertebrate head : the 

 second segment of the insects, (the prothorax of Audonin,) is, ac- 

 cording to M. Geoffrey, the second vertebra of the head of the 

 vertebrata, and so on. Upon this speculation Cuvier 3 does not give 

 any decided opinion ; observing only, that even if false, it leads to 

 active thought and useful research. 



But when an attempt was further made to identify the plan of ano- 

 ther branch of the animal world, the mollusca, with that of the verte- 

 brata, the radical opposition between such views and those of Cuvier, 

 broke out into an animated controversy. 



v 



Two French anatomists, MM. Laurencet and Meyranx, presented to 

 the Academy of Sciences, in 1830, a Memoir containing their views on 

 the organization of molluscous animals ; and on the sepia or cuttle-fish 

 in particular, as one of the most complete examples of such animals. 

 These creatures, indeed, though thus placed in the same division with 

 shell-fish of the most defective organization and obscure structure, are 

 far from being scantily organized. They have a brain, 4 often eyes, and 

 these, in the animals of this class, (cephalopoda) are more complicated 

 than in any vertebrates ; 5 they have sometimes ears, salivary glands, 

 multiple stomachs, a considerable liver, a bile, a complete double cir- 

 culation, provided with auricles and ventricles ; in short, their vital 

 activity is vigorous, and their senses are distinct. 



But still, though this organization, in the abundance and diversity 

 of its parts, approaches that of vertebrate animals, it had not been con- 

 sidered as composed in the same manner, or arranged in the same 

 order, Cuvier had always maintained that the plan of molluscs is not 

 a continuation of the plan of vertebrates. 



5 Ib. 437. s CUT. Hist. Sc. Nat. iii. 441. 



4 Geoffrey Saint-Hilaire denies this. Principes de Phil. Zoologique discutet 

 ft 1830, p. 68. 

 ' Geoffrey Saint-Hilaire, Principes de Phil. Zooloyie discutes en 1830, p. 55. 



