DEGRADATION OF ORGANISATION 71 



and let us then pass rapidly in review the fourteen classes of which 

 it is primarily composed. 



The general arrangement of animals set forth above is unanimously 

 accepted as a whole by zoologists : who dispute only as to the boundaries 

 of certain classes. In examining it I notice a very obvious fact which 

 would in itself be decisive for my purpose ; it is as follows : 



At one extremity of the series (that namely which we are accustomed 

 to consider as the anterior) we find the animals that are most perfect 

 from all points of view, and have the most complex organisation ; 

 while at the opposite extremity of the same series we find the most 

 imperfect that exist in nature — those with the simplest organisation 

 and to all appearances hardly endowed with animality. 



This accepted fact, which indeed cannot be questioned, becomes 

 the first proof of the degradation which I propose to establish ; for 

 it is a necessary condition of it. 



Another fact brought forward by an examination of the general 

 series of animals and furnishing a second proof of the degradation 

 prevailing in their organisation from one extremity to the other of 

 their chain, is the following : 



The first four classes of the animal kingdom contain animals that 

 are in general provided with a vertebral column, while the animals of 

 all the other classes are absolutely destitute of it. 



It is known that the vertebral column is the essential basis of the 

 skeleton, which cannot exist without it ; and that wherever there is a 

 vertebral column there is a more or less complete and perfect 

 skeleton. 



It is also known that perfection of faculties is a proof of perfection 

 of the organs on which they rest. 



Now although man may be above his rank on account of the extreme 

 superiority of his intelhgence as compared with his organisation, 

 he assuredly presents the type of the highest perfection that nature 

 could attain to : hence the more an animal organisation approaches 

 his, the more perfect it is. 



Admitting this, I observe that the human body not only possesses 

 a jointed skeleton but one that is above all others the most complete 

 and perfect in all its parts. This skeleton stiffens his body, provides 

 numerous points of attachment for his muscles and allows him an 

 almost endless variation of movement. 



Since the skeleton is a main feature in the plan of organisation of 

 the human body, it is obvious that every animal possessed of a skeleton 

 has a more perfect organisation than those without it. 



Hence the invertebrate animals are more imperfect than the ver- 

 tebrate animals ; hence, too, if we place the most perfect animals 



