HETEROMORPHOSIS 151 
later. Fig. 32 shows the animal two months later. The cut 
edges have coalesced, and the animal resembles somewhat a 
normal Cerianthus. The inner row of small tentacles has 
also been formed in addition to the large peripheral ones; 
but—and herein these phenomena again differ from those 
observed in Hydra—the number of tentacles is only a frac- 
tion of the number of tentacles of the normal head, corre- 
sponding to the size of the oral cut. Nor do the ends of 
the two rows of tentacles meet to form a closed circle. 
After what has been said, it need not be emphasized that 
the formation of tentacles is independent of food-supply, as 
the taking up of food is impossible without a body-cavity. 
When the pieces are too small, no tentacles whatsoever may 
be formed. 
From all that has been said, the following observations 
are easily understood. When a Cerianthus is cut completely 
in two transversely, the aboral piece forms a new head, 
bearing a normal number of tentacles, while at the lower end 
of the oral piece, which has to regenerate a foot, new substance 
is deposited upon the cut surface which restores the con- 
tinuity of the ectoderm at this end and assumes the rounded 
form of the foot. 
If head and foot are both cut from a Cerianthus, the 
middle piece forms new tentacles at the oral and a new foot 
at the aboral cut surface (the latter is formed more quickly 
than the former). But this is possible only as long as the 
pieces exceed a minimal size. 
5. I have tried to control the place where new tentacles 
are formed by contact stimuli or by orienting the animal in 
different ways against gravity andlight. All of these experi- 
ments have thus far been unsuccessful, if for no other rea- 
son, because it was impossible to maintain the animal in any 
abnormal position for any length of time. The following 
chapter will give the reasons for this behavior. 
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