TABLE 6 



rhis table gives the mesenteric formulas of thirty-two unpaired 'polyps resulting 

 from natural division and regeneration. In these specimens new complete mesen- 

 teries are distinguishable from old complete ones by their relative degree of de- 

 velopment alone. All specimens in which ?iew complete mesenteries could be dis- 

 tinguished from old only by their position with respect to an obvious boundary 

 have been excluded from this table. This exclusion is necessary in selecting a 

 group of animals that may be used for a study of the frequency of divisions in 

 different spaces, since evidence of the position of the plane of fission is lost more 

 quickly in complete endocoels and in exocoels than in incomplete endocoels. For 

 further explanation, see page 169 ff. 



.Vo. 29 exhibits an unusual condition in the presence, in the old part, of an unpaired 

 complete mesentery. Other old mesenteries are somewhat unevenly developed. 



237 



