44: HISTORY OF BRITISH ZOOPHYTES. 
use of the vesicles which are seen abundantly in many of 
the zoophytes. Some who had observed them thought that 
they were merely air-vessels to aid in floating the corallines, 
like the air-vessels which answer that purpose so well in 
many marine plants. So long as corallines were thought 
to belong to the vegetable kingdom, these vesicles had 
been regarded as the seed-vessels, and Ellis himself had 
at first been disposed to regard them as such. He now 
discovered, however, that these vesicles were the habitations 
of the young polypes,—that they might be regarded as cor- 
responding to the buds proceeding from the bodies of fresh- 
water polypes, only that, like the parent, they were defended 
by a calcareous covering, and that when they approached 
maturity they dropped off, to become independent animals, 
of the same kind as those from which they sprang. 
Not only did Ellis fully satisfy himself that what had 
formerly been considered vegetable productions were the 
habitations of little animals, by which they were formed, 
but he succeeded in rendering these little creatures per- 
manently visible, so that they could at any time be shown 
to those who were still sceptical as to their existence. Hi- 
therto he had been-.able to exhibit, when he returned to 
town, only the dried specimens, and as the polypes, on 
