12 C. M. CHILD. 



present crude technique, and this evidence is, except for certain 

 highly specialized structures, e. g., the nerve fiber, negative, so 

 far as I am aware. If an orientation of particles is the basis of 

 organic polarity and symmetry, surely the polariscope must have 

 given us more positive evidence of such orientation than we have 

 yet obtained. In the absence of such evidence the orientation- 

 hypothesis possesses a metaphysical rather than a scientific char- 

 acter. We may juggle with the ultimate particles as we please 

 and we may assume that they do all that is required to attain a 

 certain result: unquestionably we shall succeed in interpreting 

 all the phenomena of polarity in this way, but the value of our 

 interpretations is chiefly academic, and scientific proof or dis- 

 proof is impossible. 



SUMMARY. 



1. The pieces of the actinian, Harenactis attenuata, which form 

 "rings" by the union of oral and aboral ends about the whole 

 circumference, after more or less complete removal of mesenteries 

 and mesenterial muscles, may produce new discs with radially 

 arranged new mesenteries and tentacles and mouth-opening and 

 esophagus. Thus far the usual number of tentacles, twenty-four, 

 has not been attained in any case, the largest number being 

 sixteen. Such discs with from three to eight tentacles are of 

 frequent occurrence, but the formation of mouth and esophagus 

 has been observed only once. After the formation of the discs 

 they may be gradually elevated from the surface of the rings by 

 the development of a cylindrical column beneath them. 



In addition to the well-developed discs, radially as well as 

 bilaterally symmetrical and asymmetrical tentacle groups may 

 arise along the line of union on either side, or the tissue of both 

 sides may take part in the formation of a single group. 



2. These further experiments with rings extend and confirm 

 the earlier work. The new outgrowths on the rings represent a 

 more or less close approach to new individuals and involve the 

 establishment of new polarities and symmetries. They are to 

 be regarded as a form of reproduction related to the formation 

 of adventitious structures in plants. The localization of the 

 outgrowths, as well as their polarity and symmetry, have no 

 relation to the original polarity and symmetry, but are due to 



ocal conditions. 



