150 STUDIES IN GENERAL PHYSIOLOGY 
study of, the illustrations shows that the number of new 
tentacles corresponds to the size of the incision, and increases 
or decreases as the length of the incision increases or 
decreases. 
4. I cut rectangular pieces from the wall of Cerianthus 
by cutting off the head and the foot trans- 
versely, and dividing the resulting hollow 
cylinder by a longitudinal cut. These 
rectangular pieces formed tentacles upon 
only one of the four cut edges. This 
was upon that edge which was originally 
directed toward the oral pole of the 
animal. If abcd, Fig. 30, represents 
such a piece, the new tentacles sprang 
c d only from the edge ab. The three 
remaining sides remained 
‘ absolutely free from all 
evidences of new tentacles. 
BES, 0 Thus far this experi- 
ment corresponds in behavior with that of an 
analogous experiment upon Hydra.’ But 
while the piece removed from Hydra forms a 
new cylinder, and a closed body-cavity before 
the new tentacles sprout,” the tentacles upon 
the pieces of Cerianthus are formed without a 
new body-cavity originating, and even while , 
the entoderm is still exposed. The cut edges { 
that are free from tentacles may never heal & 
together, and a new body-cavity may never 
be formed. In Fig. 31 is given a picture of a fragment of 
Cerianthus bearing large tentacles while the body-cavity is 
still open and the entoderm still exposed. The cut edges 
show inversions and puckerings, to which I shall return 
1See IscHrkawa, Zeitschrift fiir wissenchaftliche Zoologie, Vol. XLIX, p. 441, 
2NussBAuM, Archiv fiir mikroskopische Anatomie, Vol. XXIX. 
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