Craspedacusta sowerbyi and Calpasoma dactyloptera — Matthews 
249 
I 1 
0.3 75 mm 
Fig. 4. Craspedacusta sowerbyi. a, Almost com- 
pletely liberated frustule; b, c , e, three atentacular 
hydranths; and d, attachment region. 
with the possible exception of frustule frag- 
ments and spherules, Buchert’s stages (Fig. 13, 
rows I, II, III) add little that is new to our 
knowledge of C. sowerbyi atentacular hydranths. 
IB. TENTACULAR HYDRANTHS OF 
MIXED CULTURES 
As previously stated, small portions of E. 
canadensis placed in Petri dishes in 30 ml of 
aged tap water contained tentacular as well as 
atentacular hydranths. Thus, the conditions un- 
der which atentacular hydranths were observed 
a pply equally to tentacular hydranths. 
Figures 6, 7, and 8 show tentacular hydranths 
either as they occur naturally on stems and 
leaves of E. canadensis or as they appear on the 
bottom of Petri dishes with detritus and algae 
(T. bombycina and F. diplo siphon ) removed. 
Thus, Figure 6B, C, and D represent tentacular 
stages which once occupied positions on a leaf 
of E. canadensis similar to those of tentacular 
stage A. However, in old, neglected cultures a 
thick algal mat may cover the bottom of the 
Petri dish and in, and frequently below, this 
mat tentacular hydranths are observed which are 
extremely hyaline. Near the bases of these old 
hydranths sometimes one, but frequently many, 
small spherules develop (Fig. GB, C, D). From 
these metamorphose, after perhaps a month or 
more of delay, small tentacular hydranths. By 
this time the parent hydranth may be completely 
consumed. Thus, with the possible exception of 
body shape these stages ( Fig. GA, B, C, D) cor- 
respond well with those of Buchert’s stages 
(Fig. 14, row IV). 
Figure 7 represents frustule budding, a phe- 
nomenon frequently observed in young, vigor - 
FlG. 5. Craspedacusta sowerbyi. a, A leaf portion 
of Elodea canadensis; b, budding frustule and its mi- 
gration ( arrows and dotted outline ); c, d, two aten- 
tacular hydranths; e, attachment region; and f, nodal 
region of E. canadensis stem. 
