THE MORPHOLOGICAL COMPOSITION OF ANIMALS. 99 



sometimes even like pairs of eyes, also have like internal 

 organs. Each has its enlargement of the alimentary canal; 

 each its contractile dilatation of the great blood-vessel; each 

 its portion of the double nervous cord, with ganglia when 





these exist ; each its branches from the nervous and vascular 

 trunks answering to those of its neighbours; each its simi 

 larly answering set of muscles; each its pair of openings 

 through the body-wall; and so on throughout, even to the 

 organs of reproduction. That_is_to_. say, every segment is_in 

 great measure a physiological whole every segment con 

 tains most of the organs essential to individual life and mul 

 tiplication: such essential organs as it does not contain, 

 being those which its position as one in the midst of a chain, 

 prevents it from having or needing. If we 



ask what is the meaning of these homologies, no adequate 

 answer is supplied by any current hypothesis. That this 

 &quot; vegetative repetition &quot; is carried out to fulfil a prede 

 termined plan, was shown to be quite an untenable notion 

 (133, 134). On the one hand, we found nothing satis 

 factory in the conception of a Creator who prescribed to him 

 self a certain unit of composition for all creatures of a par 

 ticular class, and then displayed his ingenuity in building up 

 a great variety of forms without departing from the &quot; arche 

 typal idea.&quot; On the other hand, examination made it mani 

 fest that even were such a conception worthy of being enter 

 tained, it would have to be relinquished; since in each class 

 there are numerous deviations from the supposed &quot; archetypal 

 idea.&quot; Still less can these traits of structure be accounted 



