Art. XXIX. Abstract of M. Straus-Dtirckheinis ^' Consi- 

 derations Generates sur VAnatomie Comparce des Ammaux 

 Articides" By Edward Doubleday, Esq. 



(Continued from page \2.) 



" and what is writ is writ — 



Would it were worthier ! but 1 am not now 

 That which I have been — and my visions flit 

 Less palpably before me — and the glow 

 Which in my bosom dwelt is fluttering, faint and low." 



From the effect of the different modes of gradation of the 

 organs, and from the great modifications which nature has 

 introduced into the different systems of organs, either to 

 accommodate them to the changes which their functions have 

 undergone, or to prepare them for other functions to which 

 they are destined, it results that, at certain points of the scale 

 of classification, the whole of the organization of animals is 

 found completely changed, which marks out in the animal 

 kingdom several large divisions, to which Cuvier has given the 

 name of " Embranc/iemens." The line of demarcation which 

 separates any two of these is necessarily found at the point 

 where the most important organs of one of these divisions have 

 entirely disappeared, or at least have been strongly modified ; 

 and where nature introduces successively a new series of 

 organs which are to characterize the other division. It is evi- 

 dent that by the effect of these great changes in the organiza- 

 tion of animals, a system of organs which performs the most 

 important functions in the first division, may no longer exist in 

 the next, or, at least, may only be found in a very secondary 

 condition, and subordinate to another system, which has 

 acquired over this a certain degree of preponderance. The 

 knowledge of any organ in one single division is not then suf- 

 ficient to enable us to judge of its importance ; but it is neces- 

 sary to follow it throughout its whole scale of gradation, and 

 to compare it with all those to which it is found successively in 

 relationship. This principle, so important in classification, has 

 not, perhaps, been sufficiently followed at present, and hence 

 many irregularities in the methods that have been established. 

 In fact, the anatomy of vertebrated animals having been care- 

 fully and deeply studied before much attention had been paid 



