HISTORY OE THE ROTIEERA, OR WHEEL ANIMALCULES. 479 
ought to be long enough for at least half their length to project 
beyond the outside of the apple, and if their heads (or pro- 
jecting ends) could be now embraced, each set of three, by a 
bow-shaped piece of wax, about as large as one of the divisions 
of the apple, without disturbing the arrangement already 
described, you would have a very fair representation of the 
parts of the mouth in this family. 
There is, however, one element more,— the mastax. You 
must imagine (for I cannot suggest any device for really repre- 
senting this, so as to retain the form for even an instant) three 
globules of transparent substance — really it is muscular tissue — 
surrounding the whole apparatus, one on each side, containing 
the apple, pins, and wax of that side, and the third surrounding 
the points ; — the globules united and flowing into one at their 
mutual contact, but preserving the three-lobed character of 
then’ outline. Remember that, this envelope being’ composed 
of living muscle, the contained parts have the power of motion, 
without destroying its continuity, though slightly changing its 
outline. 
Now, to understand the action of this curious mouth and jaws, 
let us farther suppose the whole apparatus carefully transferred 
to the interior of a confectioner’s show-glass, the cylindrical 
form of which will well enough represent one of our little 
friends, the Builder Animalcules. Consider the three-lobed 
mass suspended in the cylinder near the top, almost in the 
centre of the diameter, the cut faces of the apple upwards and 
horizontal. The top of the glass cylinder is covered with a flat 
piece of parchment, which expands far beyond its diameter on 
all sides, and whose edge is more or less cut into rounded lobes. 
In the middle of this sheet there is a hole or tube which leads 
down to the apparatus ; or perhaps it may be more correct to con- 
sider the parchment as forming a wide and shallow funnel, with 
an abrupt tube, which opens into the muscle-mass, just over the 
point of union of the jaws, i.e., the stem of the apple; while 
from the under side of the muscle-lobe that embraces the points 
another tube leads downward to the stomach. 
Of course all this is but a rude and homely comparison ; but 
it will probably make the whole process of the reception of food 
in these creatures, with the uses of the various surrounding 
organs, far clearer than any amount of mere technical description, 
however accurate, could do. 
The action, then, is as follows : — The edge of the expanded 
disk, which I represent by the parchment funnel, is, as I have 
already said, crowded with vibrating cilia, which produce strong 
currents in the surrounding water. As the ciliary beatings are 
all in one direction, the impulse given to the water is circular (we 
may consider it such at least), and thus a whirlpool is formed, the 
