THE NATURE OF SPONGES. 
175 
which are contractile vesicles, which make the systole and 
diastole movements very slowly. The spiculae are “ very 
slender, slightly curved, small-shaped bodies.” From the 
position of the cilia of these monads Professor Clark considers 
that they only produce local currents, and that the general cir- 
culation is maintained by the contraction and expansion of the 
body mass in general. By consulting the figures in the plate 
and the references thereto at the end of this article, the reader 
will understand the preceding descriptions, and know what to 
look for if such an organism falls in his way. 
In “Annals Nat. Hist. 1859,” vol. iii. p. 14, Mr. Carter 
describes monociliated cells of spongillse, and he appends 
figures of those belonging to S. plumosa and S. alba , the 
former having two ear-like points projecting forwards, and 
showing particles of indigo it had taken in. 
In another paper in the same volume Mr. Carter describes 
“ spherical bodies ” in spongillse, and asks, “ Are they each 
animals of the spongilla, and analogous to the polypes of a 
polypidom ; or is this typical portion to be considered as a 
single animal, and the spherical bodies as the digesting organs 
situated in the cavities of the gelatinous mass, or a stomach 
with the branch canals as a vent ? ” Further remarks appear 
to show an inclination to the former view. 
In vol. vi. p. 329, 1870, will be found another of Mr. H. J. 
Carter’s papers 66 On the Ultimate Structure of Marine Sponges,” 
in which the following passage occurs : “ Ampullaceous sac is 
the term I applied to certain groups of unciliated and mono- 
ciliated sponge cells, or monad-like bodies, which are tessellated 
together in a globular form, and scattered plentifully here and 
there throughout the sponge, so as to make up the greater part 
of its bulk. The globular form presents a circular opening, or 
transparent area, through which the cilia may be observed to 
play internally ; and when the young spongilla is grown from 
the seed-like body, and a solution of carmine is put into the 
water around it, the new globular bodies alone become coloured. 
.... Hence the little globular bodies are clearly the animal 
expression of the sponge in particular, as they are respectively 
the only mouths and stomachs of the sponge — in short, the 
nutritive apparatus, all the rest being subsidiary.” He proceeds 
to say that when spongillse fed with carmine are torn to pieces, 
the “ monad-like bodies,” which he calls “ sponge cells,” of 
which the ampullaceous sac is composed, are found to have 
taken in the carmine, while the absence of the cilium in some 
and not in others may be explained, as just stated, by its being 
retractile. 
Carter likewise states that he detected the 66 ampullaceous 
sac ” in marine sponges, both siliceous and calcareous, and in 
each of them it is the u eating organ.’ 
