78 Dr Treviranus on the 



versified its excitability. The number of these points of con- 

 tact increase with the advancement of the intelligence, which 

 necessitates a proportionate increase in the variety and perfection 

 of the several organs. The intellectual faculty is more perfect 

 in man than in any other terrestrial existence. He, therefore, 

 merely in an organic point of view, stands at the head of the 

 scale of animals. But this does not oblige us to suppose that 

 in him every organ has reached the maximum of its develop- 

 ment. An important line of distinction must here be drawn 

 between the organic sphere of the sensitive and of the simply 

 organic life. With respect to the former class of organs man 

 is decidedly at the head of all animals, but by no means in re- 

 spect to the latter. His alimentary apparatus, for instance, is 

 not nearly so complicated as in many other animals. Between 

 him and the lowest existences there are many members, of which 

 one cannot be said to occupy a higher place than another. One 

 being is best adapted for one purpose, and another for a diffe- 

 rent purpose. They can only be placed in a linear series, by 

 arranging them according to the type of some one of their or- 

 gans. 



2. An original form may be very easily supposed, out of which 

 all living things are developed. This development is not in one 

 but in several directions. Each of these principal directions 

 again give rise to new subdivisions, so that the whole assumes 

 somewhat of an arborescent form. Different twigs, however, of 

 one of the branches often unite those of another higher or low- 

 er in the scale. In the midst of all these diversities, a general 

 similarity persists between the various organisms and their se- 

 veral parts, which enables us to trace them up to a common 

 fundamental form. No conclusions, however, can be drawn 

 from the similarity of two forms, regarding their respective 

 superiority or inferiority in point of development. Such simi- 

 larity may result from the lateral concurrence of two forms de- 

 rived from totally different twigs. Insects, for example, resem- 

 ble the vertebrata in some of their organs, but are otherwise so 

 different from them in all their parts, that this partial exception 

 cannot be considered to result from a higher development of 

 the form peculiar to insects. As in the higher animals, so we 

 can likewise distinguish in the alimentary canal of insects, a se- 



