4i6 



L. II. HYMAX. 



6. Relation of Size of the Regenerated Oral Hydrant h to the 

 Diameter of the Stem. Some experiments were performed on this 

 matter. It was found that the size of the hydranth is slightly 

 larger in stout than in slender stems when other factors are 

 eliminated. This difference is detectable only when the difference 

 in diameter of the stems is considerable. In Table III., where 

 there are but small differences in diameter, no definite relation 

 between dimensions of regenerated oral hydranths and diameter 

 of the stems appears. But when stems differing markedly in 

 diameter are compared the dimensions of the regenerated oral 

 hydranths are seen to bear some slight relation to the diameter 

 of the oral end of the pieces. One experiment of this kind is 

 given in Table IV. Stout and slender stems from the same 

 colony, of the same length, and cut at the same apical levels 

 were allowed to regenerate and the resulting oral hydranths 

 measured as in the preceding section. There were ten stems of 

 each lot; these have been averaged in the table for brevity. 



TABLE IV. 



DIMENSIONS OF REGENERATED ORAL HYDRANTHS WITH REFERENCE TO THE 

 DIAMETER OF THE APICAL END OF THE ORIGINAL STEMS. 



Ten pieces in each lot, pieces 20 mm. long. Figures, units of the micrometer 



scale. 



Lot of Slender Stems. 



Lot of Stout Steins. 



Table IV. shows that in the stouter stems the dimensions of the 

 hydranth are slightly larger on the average than in the slender 

 stems. The chief difference is in the width of the hydranth. 



