250 
Fig. 6. Portion of E. canadensis leaf. A, Tentacular 
hydranth; B and C, tentacular hydranths forming 
spherules; and D, metamorphosis of a spherule into 
a small tentacular hydranth. 
ons tentacular hydranths. This approximates 
frustule budding in atentacular hydranths, ex- 
cept that in tentacular hydranths the process 
may occur anywhere along the hydranth column, 
not necessarily near the hypostomal region. 
These small frustules may form spherules which 
develop tentacles (A); or may form tentacles 
directly at their thinner end (B); or may form 
tentacles simultaneously at both ends (C) even 
before the frustule attaches. Thus, from a frus- 
tule axle, tentacles may radiate like spokes from 
each end. Later, one end slowly rises from the 
bottom of the Petri dish and forms an asym- 
metrical V, i.e., one side is shorter than the 
other. Only when the complete metamorphosis 
from frustule to tentacular hydranth is observed 
can one say with certainty which is bud and 
which is parent. This, as previously stated, is 
quite different from true hydranth budding. 
Again, except for slight differences in body 
PACIFIC SCIENCE, Vol. XX, April 1966 
frustule forming a small tentacular hydranth; and C, 
frustule forming tentacles at both ends. 
shape, these stages (Fig. 1 A. B, C) correspond 
well with those of Buchert’s stages (Fig. 14, 
row V ) . 
Figure 8 represents a piece of E. canaden- 
sis on which hydra nth-budding tentacular hy- 
dranths {A, B, C, D) and atentacular hydranths 
are located; the latter, for the sake of clarity, 
are omitted although in leaf axils of this very 
portion atentacular hydranths occurred. This 
point is stressed, for it is important that we 
realize that both tentacular and atentacular hy- 
dranths can occur simultaneously under the 
same environmental conditions. 
Figure 8 B is of particular interest because, 
since atentacular hydranths had apparently lost 
their ability to form medusa-buds, this function, 
I reasoned, had been taken over by small frus- 
tules (Fig. SB. a). Food brought to tentacles 
elicited little or no response, but this was ex- 
pected, since readiness to forage should have 
been preceded by movements of tentacles and 
velum. I waited. Days passed. Impatient at the 
