214 GRAND STRATEGY OF EVOLUTION 



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FIGURE 5. DIAGRAM TO ILLUSTRATE TRIAXIAL GROWTH. A. seen from the 

 neural side, B, from the haemal. The metameres formed at the growing 

 point, g. p., (blastopore, teloblasts, telopore) are indicated by numbers: 

 Growth to right and left of the median neural line is indicated by arrows; 

 serial homology and bilateral symmetry, by letters, those on one side being 

 the mirror image of those on the other. Cephalization, or the specializa- 

 tion and breaking down of metamerism at the head end, has already 

 begun. The figure is based on the arachnid type of triaxial growth. 



the chief sources of life's constructive supplies, and the 

 chief sources of danger. (2) It provides maximum 

 economy in the grouping of all the great organic sys- 

 tems of conveyance and support, such as nervous, ali- 



