7 8 Traces of Unity 



case where, in consequence of the disappearance of inter- 

 nodal septa in a branch or stem, several nodes may come 

 to be traversed by a continuous pith-cavity : indeed, the 

 pierced nodes in such a case, as in that of the reed, is 

 the nearest approach in plants to the zonular type, which 

 enters so largely into the construction of animal bodies 

 is perhaps the simplest expression of the archetype in 

 its zonular phase. Nay it is possible that the set of 

 pipes in the hand of Pan who is a personification of 

 Nature may point quite as much to this archetypal 

 significance of the reed as to the harmonious dance of 

 all things to the music of the spheres. 



On following out the progressive evolution of the 

 animal frame the next step appears to consist in a 

 partial or complete division of the zone into segments. 

 Just as the zone itself is formed out of the cell by the 

 increase of the equatorial region at the expense of the 

 polar regions, so now the division of the zone into seg- 

 ments would seem to be formed by the development of 

 certain parts of the zone at the expense of the inter- 

 mediate parts. The effect of the segmentation is mani- 

 fested in the formation of ganglia in the nervous layer, 

 of muscular masses in the muscular layer, of cardiac 

 centres in the vascular layer, of bony masses in the 

 osseous layer, and so on. The ambulacral lines of the 

 starfish or sea-urchin are traces of the division of the 

 zone into segments. The tentacles of the polype and 

 of the cephalopod are formed in part by the division 

 of the edge of the zone into segments, and in part 

 by the subsequent growth of the portion of the edge 

 belonging to them ; and the multiplication of certain 

 polypes by " fission " is only an extension of the same 

 process which is seen at work in the cutting out of the 

 tentacles. 



