128 
OTTO C. GLASER 
other indigestible bodies from nematocysts, but this inability 
to select is not shared by the cnidophages, for so far as I know, 
these ingest only nematocysts. 
The cnidophages are derived from a zone of embryonic'' cells, 
located just distally to the ciliated canal. Fig. 6, a drawing of the 
proximal portion of a longitudinal section which happened not 
to strike the canal, shows the embrj^onic zone {EMB. Z.). Its 
cells have either no boundaries or incomplete ones; the nuclei are 
large and contain coarse chromatin granules; and the cytoplasm is 
undifferentiated. From this region of proliferation the oldest cells 
CMDfYS 
Fig. 6 Median longitudinal section through ceras; EMBZ., embryonic zone; 
CNDPH., cnidophages; CNDCYS., cnidocysts. 
are pushed upward and enter the zone of cnidophages (CNDPH.) 
where, after ingesting a number of nettles inversely variable 
with the size of the engulfed capsules, the}^ become converted into 
cnidocysts (CNDCYS.). 
No single description of the cnidophore would prove satisfactory 
since the various zones that compose it present phases which 
depend in part on the age of the appendage, in part on the num- 
ber of nematocysts ingested. In cerata in which '^feeding" is 
actively going on, or in which it might go on, certain cells show 
evidence of pseudopodial activity. In the transverse section, 
fig. 7, the lumen of the cnidophore is traversed and rendered 
labyrinthine basally, by projections from its bounding cells. Pro- 
cesses from several cells may fuse into larger bridges with, at 
