4:88 HISTOEY OF PHYSIOLOGY. 



gard to the beak, and the oesophagus with regard to the liver, should 

 have positions corresponding to those in vertebrates ; but the positions 

 of these organs are exactly contrary to the hypothesis. How, then, 

 can you say," he asks, " that the cephalopods and vertebrates have 

 identity of composition, unity of composition, without using words in a 

 sense entirely different from their common meaning ?" 



This argument appears to be exactly of the kind on which the 

 value of the hypothesis must depend. 14 It is, therefore, interesting to 

 see the reply made to it by the theorist It is this : " I admit the 

 facts here stated, but I deny that they lead to the notion of a different 

 sort of animal composition. Molluscous animals had been placed too 

 high in the zoological scale ; but if they are only the embryos of its 

 lower stages, if they are only beings in which far fewer organs come 

 into play, it does not follow that the organs are destitute of the rela- 

 tions which the power of successive generations may demand. The 

 organ A will be in an unusual relation with the organ C, if B has not 

 been produced ; if a stoppage of the developement has fallen upon 

 this latter organ, and has thus prevented its production. And thus," 

 he says, " we see how we may have different arrangements, and divers 

 constructions as they appear to the eye." 



It seems to me that such a concession as this entirely destroys the 

 theory which it attempts to defend ; for what arrangement does the 

 principle of unity of composition exclude, if it admits unusual, that is, 

 various arrangements of some organs, accompanied by the total ab- 

 sence of others ? Or how does this differ from Cuvier's mode of stat- 

 ing the conclusion, except in the introduction of certain arbitrary 

 hypotheses of developement and stoppage? "I reduce the facts," 

 Cuvier says, " to their true expression, by saying that Cephalopods 

 have several organs which are common to them and vertebrates, and 

 which discharge the same offices ; but that these organs are in them 

 differently distributed, and often constructed in a different manner; 



14 I do not dwell on other arguments which were employed. It was given 

 as a circumstance suggesting the supposed posture of the type, that in this way 

 the back was colored, and the belly was white. On this Cuvier observes (Phil. 

 Zool. pp. 93, 68), " I must say, that I do not know any naturalist so ignorant as 

 to suppose that the back is determined by its dark color, or even by its position 

 when the animal is in motion ; they all know that the badger has a black 

 belly and a white back ; that an infinity of other animals, especially among 

 insects, are in the same case ; and that many fishes swim on their side, or with 

 their belly upwards." 



