24 George Thomas Hargift 



stated that aniitotically dividing nuclei are usually of large size 

 and are distinguished in many cases by a "specially intense sec- 

 retory . . . activity." This "secretory activity" would be 

 necessary for a time at least in Eudendrituii and Peiuiaria, while 

 the perisarc was being secreted around the protruding coenosarc, 

 and amitotic nuclear division may thus be partially explained 

 in 'these two species. In Tiibularia, however, where the hy- 

 dranths regenerate within the perisarc and only a few cells at 

 the end secrete a new perisarc, the amitotic division could not be 

 explained in this way. Indeed, while this direct division may 

 be partially explained in the ways already considered, it seems 

 to be too prevalent to be accounted for by these conditions alone. 

 Furthermore, the cells do not seem to be in a degenerate con- 

 dition, and are the cells from which the hydranths or tentacles 

 are formed. It may be the result of special conditions, which, as 

 Wilson states, has been conclusively proven to be the case in 

 lower forms, though as to just what the special conditions might 

 be it is difficult to conjecture. However, this phenomenon can 

 not be fully explained till further investigations have been made. 



C«NCLU.SIONS 



1. Gravity has no apparent influence on the regeneration of 

 Tiibularia crocca and Pcniian'a tiarclla. 



2. Contact determines in some measure the kind of regeneration 

 and the direction of growth in Eudcndriinii raniosuni and Pen- 

 naria fiarella. 



3. In Tiibularia crocca there is a marked polarity, hydranths 

 appearing more abundantly and in a shorter time at the distal 

 ends. 



4. Pieces of Tiibularia crocca and Tiibularia tciiclla of about 

 3 to 4 mm. length failed to regenerate. 



5. In Tiibularia crocca the method of regeneration is about 

 as found by other authors. The cut end closes over, the liquid 

 in the enteric cavity begins to circulate, and red pigment is de- 

 posited in the hydranth region. Tentacles appear first as longi- 

 tudinal folds or ridges and are pinched off from the hydranth 

 body to assume the final form and size while still within the 



298 



