330 Mr. H. J. Carter on the Ultimate 
in some, and not in others, may be explained, as just stated, 
by its being retractile. 
urther, it was observed that after a time those portions of 
the carmine which were unappropriated to nourishment were 
rejected, and, as they fell into the adjoining canal of the excre- 
tory system, were thus voided. But whether they passed into 
the excretory canal through the circular opening or transpa- 
rent area in the ampullaceous sac, or through another openmg 
in it unseen, or directly through the substance of the body ot 
the sponge-cell, Ameba-like, into the excretory canal, I could 
not determine. 
So far, then, it was evident that the ampullaceous sac is the 
expression of the alimentary apparatus. 
"o conceive that the nourishing portions of the food, after 
having been resolved into chime in these sponge-cells, subse- 
quently passed, by endosmosis, into the general mass to be- 
in the excretory canals), began to be separated from its nutri- 
tive portion and its particles to fall from the sponge-cells into 
the excretory canals and so be voided. 
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