$M THE NEW EVOLUTION '^'^ 



or jointed worms have lost all traces of an internal 

 calcareous skeleton, a structure very highly developed 

 in the echinoderms ; the mollusks are almost entirely 

 w^ithout a trace of segmentation; vv^hile the arthropods 

 are w^ithout a perivisceral coelome or internal cal- 

 careous structures, and their endoderm and excretory 

 organs are very much reduced. 



There can therefore be no relationship whatever 

 between the developmental figure represented by the 

 horses from Eohippus to the modern type and the 

 figure representing the interrelationships of the sev- 

 eral phyla. 



Since both addition and subtraction are involved 

 in the differences between the phyla we must believe 

 — if we are to be consistent — that all of the various 

 phyla are on the same developmental plane, or in 

 other words that they came into existence through 

 derivation from a common ancestor or ancestral type 

 which was possessed of the potentiality for producing 

 each and all of them. 



To express this in concrete terms, it is impossible 

 to believe that the echinoderms, lacking half of each 

 body segment and a nephridial system, the annelids, 

 with no trace of an internal calcareous skeleton, the 

 mollusks, without segmentation, or the arthropods, 

 without a perivisceral coelome or an internal cal- 

 careous skeleton, can represent steps along a develop- 

 mental line running to the vertebrates in which the 

 body segments are composed of two similar halves 

 one on either side of the midline, in which there is 

 always an elaborate nephridial system, in which there 



[2^06] ~ 



