248 
PACIFIC SCIENCE, Vol. XX, April 1966 
Figure 1 (a, d) and Figure 2 (a, c) are really 
not comparable with those of Figure 3 {a, b, c, 
e) or with those usually shown by other workers. 
As will be explained later, hydranth buds form 
as lateral outpocketings of existing hydranths, 
and thus size differences accompany age differ- 
ences. Hydranths of Figure 1 (a, d) and Figure 
2 (a, c) are of the same size and the same 
age. This will be explained subsequently under 
frustule development. 
Figure 4 with its almost completely liberated 
frustule (a), its three hydranths (b. c, e), its 
attachment region (d), and Figure 5 with its 
two hydranths (c,d), its attachment region (e) 
on the node (/) of E, canadensis and its frus- 
tule (b) correspond well with those of Bucher t’s 
stages (Fig. 13, row III), although the actual 
site of frustule budding is different. Payne 
(1924:430, pi 10, fig. 64) also indicates that 
frustule budding occurs in the lower rather than 
in the upper one-third of the hydranth’ s column. 
Although the probable purpose of their figures 
was more to record frustulation than to depict 
its actual site, nevertheless, the hypostome re- 
gion with its higher metabolic rate (Burnett, 
1961:427) is the one usually selected. Thus, 
1 — — — — — — — H 
200 p 
Fig. 2. Craspedacusta sowerbyi. a , c, Atentacular 
hydranths developing from both ends of the frustule; 
and b, attachment. 
nema bombycina and Fremyella diplosiphon) 
have been removed. In Figure 1 the two aten- 
tacular hydranths (a, d) and the centrally lo- 
cated attachment point (c) correspond well 
with Bucher t’s stages (Fig. 13, row I), except 
that my developing bud (b) ultimately became 
a hydranth whereas his became a medusa ( a ). 
However, one need only refer to Payne (1924: 
430, pi. 10) for confirmation of Buchert’s row 
I stages. 
Figure 2 with its two hydranths (a, c) 9 its 
basal attachment region ( b ) , and Figure 3 with 
its four hydranths {a, b, c, e) and its basal 
attachment region (d) correspond well with 
Buchert’s stages (Fig. 13, row II). It should 
be pointed out, however, that my hydranths in 
S— 1 
0-3 mm 
Fig. 3. Craspedacusta sowerbyi. a, b, c, e, Four 
atentacular hydranths; and d, attachment region. 
