68 C. M. Child 
oral tentacles are undergoing atrophy at their tips, but the smaller 
aboral tentacles are still intact. 
The ability to produce tentacles at the aboral end exists through- 
out the cesophageal region of Harenactis. Every piece from this 
region which does not collapse and die within the first few days 
after section produces them. ‘Their number and relation to the 
mesenteries 1s the same as at the oral end; in fact an aboral disc 
thus formed can scarcely be distinguished after a few days from 
an oral disc, except by the smaller size of its tentacles. 
* 
Fig. 2 Csophageal piece (between lines a and 5, Fig. 1) in section with oral and heteromorphic 
tentacles. 
Partial Aboral Discs in the Gisophageal Region 
Partial isolation of some portion of the cesophageal region from 
the regions aboral to it is readily accomplished by a lateral incision 
involving both body-wall and cesophagus on one side (Fig. 3). 
This is the method employed for the production of lateral partial 
discs in Cerianthus (Child, ’05), and partial discs arise in the same 
manner in Harenactis. 
The course of restitution in these cases is briefly as follows: 
The contraction following the operation approximates the cut 
margins of cesophagus and body-wall above and below the cut 
and union occurs as indicated in Fig. 4, leaving a new lateral open- 
ing into the cesophagus. Within two or three days tentacles begin 
to develop proximal to this opening, their number being deter- 
mined by the number of intermesenterial chambers cut across by 
the incision: thus far these cases show the same results as Cerian- 
thus. A few days later, however, tentacles also begin to develop 
distal to the opening, 1. e., at the aboral end of the partially isolated 
cesophageal region (Fig. 5). When the incision lies proximal to 
the level of the mesenterial ostia these heteromorphic tentacles 
