ON THE DIGESTIVE APPARATUS OF Infusoria. 419 
which are supposed to unite the stomachs together; and secondly, many years 
since, I observed in various species of Infusoria , that the supposed stomachs in 
the inside of the same moved round with greater or less rapidity, in a manner 
quite similar to the globules in the rotatory motion of the cells of Chara . More 
recently I have often seen when the Vorticella has received from nine to fifteen 
balls of Indigo into its body, that they have turned continuously around a 
middle point, and have thus shewn very precisely, that here an intestinal column» 
which unites the stomachs with each other, having one end at the mouth and 
the other at the anus, can have no existence. 
Then what are these nearly equal-sized globules and vesicles which are seen 
in the inside of Infusoria , and which have been considered as stomachs ? This 
question will be generally asked, and I have put the same to myself, till, 
by continual observation, I have discovered the origin of these globules and 
vesicles. 
The true Infusoria are vesicular animals, whose interior is filled with a 
mucous and somewhat saline substance. The thickness of the membrane w 7 hich 
forms the vesicles is in some of these animals distinctly perceived; and in various 
species I have been able to observe, very clearly, in this membrane a perceptible 
spiral structure, so that in this view the fabric of these Infusoria appears to me 
to have on the whole a structure similar to that of the cells of plants. In the 
larger Infusoria there exists a cylindrical canal (digestive canal), which proceeds 
from the opening of the mouth obliquely through the membrane forming the 
animal; the lower end of this canal is more or less distended by the reception of 
food, and ordinarily to the extent of the globules which occur in the interior of 
the same Infusoria. The inside surface of this part of the digestive tube is 
covered with cilia, through whose motion the received matter, the food as well as 
foreign matters, are driven round in a circle with extraordinary velocity, till they 
are rolled together into a regular globule. During this formation of the globule, 
the stomach (for nothing else can this organ be considered) is open in connection 
with the digestive tube, and through the ciliary apparatus new matter is con¬ 
stantly driven into this canal and into the stomach; but whether the digestive 
canal between the opening of the mouth and the stomach is also clothed with 
cilia, I have not yet been able positively to observe. 
At last the globule of received matter, having attained the size of the stomach, 
is pushed down to the other end of the same, and driven into the cavity of the 
animal; this is followed by the formation of another globule inside the stomach, 
if the surrounding fluid contain solid matter; this second globule is also driven 
into the cavity of the animal; and pushes now the first globule with the inter¬ 
vening mucus further on before it, and thus proceeds without cessation the 
formation of similar globules out of the ingested matter. These are the globules 
VOL. IV.—NO. xxxii. 3 i 
