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POPULAR SCIENCE REVIEW. 
tlie aperture between the slippers. Here the malic! press upon 
the prey (suppose it an Eu-glena), with rapid and forceful forward 
movements, until they gradually drive it through the aperture 
downward. It is now free from the jaws, but does not pass 
into the stomach, but comes up around the sides of the appa- 
ratus again into the upper area of the crop, and whirling around 
with its companions, is presently again laid hold of by the jaws. 
I have seen the process go on many times in quick succession, 
upon the same individual Engl cm a, which seemed to sustain 
little damage from the ordeal; still, I suppose it is bruised at 
every turn, and thus the digestive action is facilitated, which 
seems to commence in the crop. That the prey is not crushed 
or its form seriously altered, is clearly perceived from the fleet's 
which I have seen composed of the various species of Monads, 
&c., dead, indeed, and mixed with turbid green matter, but 
scarcely at all changed in outline. Larger prey is sometimes 
devoured, which cannot be forced through the aperture of the 
incus ; thus, I have seen in the crop at once two Goluri (minute 
but highly-organised Rotifera), each of which is larger than the 
whole dental apparatus. The contents of then’ shells appeared 
to be nearly dissolved. 
Digestion is completed in a globose stomach (plate iii. </), 
opening out of the crop below the jaws. This is a viscus of con- 
siderable capacity, of which the walls are thickened by being 
lined with large turgid cells, of a yellowish-green hue, which 
probably secrete bile, and pour it into the stomach-cavity while 
digestion is proceeding*, thus performing the functions of a liver. 
The colouring matter of the food itself, when vivid green ani- 
malcules have been swallowed, may be seen running- in among 
the cells, and diffusing itself through the thickened walls, leav- 
ing a hue which is visible after the food has passed away from 
the tubular centre. This latter, the true stomach, is very dilat- 
able and contractile. It is separated — by a constriction, or 
perhaps by a proper diaphragm, sometimes very distinctly visi- 
ble, but not always — from a globose intestine of nearly equal 
capacity, which communicates by a rather long rectum, ordi- 
narily wrinkled longitudinally, but capable of great expansion, 
with the cloaca, which, as I have said, is very protrusile.* It 
* Dr. Arlidge (Pritchard’s “ Infusoria” Ed. 4, p. 419) appears to confound 
the intestine with the rectum in the entire class. I find, however, no diffi- 
culty in distinguishing, in almost all Rotifera, a true intestine, situate below 
the true digesting stomach, from a rectum, a canal into which the fcecal pallet 
is discharged, and in which it occasionally remains a few minutes before it is 
expelled through the cloaca. By this last term I mean the common orifice of 
the digestive and the reproductive organs. Dr. Leydig considers, and I have 
come to the same conclusion, from the same premises, myself, that the com- 
plete and rapid manner in which the cloacal orifice closes, after the extrusion 
of the foecal pellet, indicates the existence of a sphincter muscle there. 
